Server: Use strict comparators

This is a minor issue, but could probably help avoiding some bugs in the future.

Here is the report from the app checker

```
Analysing ownnote/controller/pagecontroller.php
1 errors
line 45: == - is discouraged
Analysing ownnote/lib/backend.php
49 errors
line 56: == - is discouraged
line 57: == - is discouraged
line 57: == - is discouraged
line 73: == - is discouraged
line 100: == - is discouraged
line 100: == - is discouraged
line 101: == - is discouraged
line 102: == - is discouraged
line 102: == - is discouraged
line 103: == - is discouraged
line 104: == - is discouraged
line 104: == - is discouraged
line 105: == - is discouraged
line 106: == - is discouraged
line 106: == - is discouraged
line 107: == - is discouraged
line 108: == - is discouraged
line 108: == - is discouraged
line 109: == - is discouraged
line 110: == - is discouraged
line 110: == - is discouraged
line 111: == - is discouraged
line 140: == - is discouraged
line 140: == - is discouraged
line 140: != - is discouraged
line 143: == - is discouraged
line 155: != - is discouraged
line 172: != - is discouraged
line 189: == - is discouraged
line 189: == - is discouraged
line 200: == - is discouraged
line 212: == - is discouraged
line 213: == - is discouraged
line 213: == - is discouraged
line 251: == - is discouraged
line 253: != - is discouraged
line 257: == - is discouraged
line 274: == - is discouraged
line 274: == - is discouraged
line 304: == - is discouraged
line 315: != - is discouraged
line 317: != - is discouraged
line 346: != - is discouraged
line 348: != - is discouraged
line 364: == - is discouraged
line 379: != - is discouraged
line 384: != - is discouraged
line 385: != - is discouraged
line 387: != - is discouraged
Analysing ownnote/templates/admin.php
3 errors
line 15: == - is discouraged
line 16: != - is discouraged
line 19: != - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/application/controllers/uploader.php
2 errors
line 63: == - is discouraged
line 63: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/libraries/Upload.php
18 errors
line 214: != - is discouraged
line 268: == - is discouraged
line 281: == - is discouraged
line 392: == - is discouraged
line 415: == - is discouraged
line 488: == - is discouraged
line 540: == - is discouraged
line 586: == - is discouraged
line 591: == - is discouraged
line 629: == - is discouraged
line 646: != - is discouraged
line 702: == - is discouraged
line 828: == - is discouraged
line 833: != - is discouraged
line 903: == - is discouraged
line 910: == - is discouraged
line 951: == - is discouraged
line 986: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/libraries/Image_lib.php
74 errors
line 146: == - is discouraged
line 204: == - is discouraged
line 252: == - is discouraged
line 273: != - is discouraged
line 273: != - is discouraged
line 286: == - is discouraged
line 289: == - is discouraged
line 295: == - is discouraged
line 295: == - is discouraged
line 299: == - is discouraged
line 300: == - is discouraged
line 303: != - is discouraged
line 305: == - is discouraged
line 311: != - is discouraged
line 313: == - is discouraged
line 319: != - is discouraged
line 324: != - is discouraged
line 329: != - is discouraged
line 399: == - is discouraged
line 406: == - is discouraged
line 406: == - is discouraged
line 419: == - is discouraged
line 419: == - is discouraged
line 426: == - is discouraged
line 426: == - is discouraged
line 455: == - is discouraged
line 455: == - is discouraged
line 457: != - is discouraged
line 470: == - is discouraged
line 480: == - is discouraged
line 503: == - is discouraged
line 516: == - is discouraged
line 525: == - is discouraged
line 562: == - is discouraged
line 578: == - is discouraged
line 582: == - is discouraged
line 631: == - is discouraged
line 654: == - is discouraged
line 658: == - is discouraged
line 731: == - is discouraged
line 775: == - is discouraged
line 817: == - is discouraged
line 853: == - is discouraged
line 902: == - is discouraged
line 905: == - is discouraged
line 935: == - is discouraged
line 958: == - is discouraged
line 991: == - is discouraged
line 1022: == - is discouraged
line 1025: == - is discouraged
line 1031: == - is discouraged
line 1033: == - is discouraged
line 1051: == - is discouraged
line 1102: == - is discouraged
line 1130: == - is discouraged
line 1133: == - is discouraged
line 1283: == - is discouraged
line 1283: == - is discouraged
line 1286: == - is discouraged
line 1286: == - is discouraged
line 1294: != - is discouraged
line 1294: != - is discouraged
line 1299: != - is discouraged
line 1299: != - is discouraged
line 1301: == - is discouraged
line 1328: == - is discouraged
line 1343: == - is discouraged
line 1394: == - is discouraged
line 1398: == - is discouraged
line 1398: == - is discouraged
line 1403: == - is discouraged
line 1407: == - is discouraged
line 1500: == - is discouraged
line 1507: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/helpers/language_helper.php
1 errors
line 47: != - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Hooks.php
3 errors
line 75: == - is discouraged
line 160: == - is discouraged
line 189: != - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/CodeIgniter.php
5 errors
line 95: != - is discouraged
line 105: == - is discouraged
line 105: == - is discouraged
line 195: == - is discouraged
line 268: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Lang.php
6 errors
line 69: == - is discouraged
line 83: == - is discouraged
line 86: == - is discouraged
line 90: != - is discouraged
line 121: == - is discouraged
line 145: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Security.php
5 errors
line 153: != - is discouraged
line 411: != - is discouraged
line 462: == - is discouraged
line 478: == - is discouraged
line 855: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Utf8.php
3 errors
line 46: != - is discouraged
line 47: == - is discouraged
line 156: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Common.php
13 errors
line 75: == - is discouraged
line 75: == - is discouraged
line 194: != - is discouraged
line 353: == - is discouraged
line 419: == - is discouraged
line 424: == - is discouraged
line 429: == - is discouraged
line 436: == - is discouraged
line 440: == - is discouraged
line 440: == - is discouraged
line 476: == - is discouraged
line 485: == - is discouraged
line 491: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Router.php
7 errors
line 146: == - is discouraged
line 158: == - is discouraged
line 229: == - is discouraged
line 266: == - is discouraged
line 449: == - is discouraged
line 505: != - is discouraged
line 512: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Benchmark.php
1 errors
line 74: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Config.php
9 errors
line 67: == - is discouraged
line 98: == - is discouraged
line 191: == - is discouraged
line 234: == - is discouraged
line 254: == - is discouraged
line 259: == - is discouraged
line 261: == - is discouraged
line 296: == - is discouraged
line 312: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/URI.php
20 errors
line 87: == - is discouraged
line 90: == - is discouraged
line 106: != - is discouraged
line 106: != - is discouraged
line 114: != - is discouraged
line 121: == - is discouraged
line 121: != - is discouraged
line 134: == - is discouraged
line 139: == - is discouraged
line 164: == - is discouraged
line 214: == - is discouraged
line 253: == - is discouraged
line 253: != - is discouraged
line 253: != - is discouraged
line 280: != - is discouraged
line 302: != - is discouraged
line 419: == - is discouraged
line 442: == - is discouraged
line 559: == - is discouraged
line 563: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Input.php
19 errors
line 260: == - is discouraged
line 260: != - is discouraged
line 264: != - is discouraged
line 264: == - is discouraged
line 268: != - is discouraged
line 268: == - is discouraged
line 272: == - is discouraged
line 272: != - is discouraged
line 435: == - is discouraged
line 445: == - is discouraged
line 477: == - is discouraged
line 477: == - is discouraged
line 497: == - is discouraged
line 499: == - is discouraged
line 509: == - is discouraged
line 525: == - is discouraged
line 598: == - is discouraged
line 645: == - is discouraged
line 703: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Output.php
7 errors
line 158: == - is discouraged
line 192: == - is discouraged
line 340: == - is discouraged
line 373: == - is discouraged
line 412: == - is discouraged
line 466: == - is discouraged
line 516: == - is discouraged
Analysing ownnote/js/tinymce/plugins/jbimages/ci/system/core/Loader.php
14 errors
line 206: == - is discouraged
line 242: == - is discouraged
line 259: == - is discouraged
line 329: == - is discouraged
line 329: == - is discouraged
line 452: != - is discouraged
line 619: == - is discouraged
line 691: == - is discouraged
line 752: != - is discouraged
line 760: == - is discouraged
line 827: == - is discouraged
line 981: == - is discouraged
line 989: == - is discouraged
line 1048: == - is discouraged
Analysing ownnote/appinfo/app.php
1 errors
line 34: OC_L10N - static method call on private class
App is not compliant
```