Unsafe floating-point comparisons with '==' or '!='

Comparison results of floating-point values with the `==` or `!=` operators depend on compiler optimizations, architecture and precision and there are corner cases like NaN, infinity or `-0.0`.

Tag 4.12.5 produces the following warnings in GCC and CLang using `-Wfloat-equal`:

```
../../nuklear.h:6546:10: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:6546:22: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:7297:11: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:7904:39: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:7939:16: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9340:34: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9340:49: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9363:34: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9363:49: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9387:22: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9387:37: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9411:19: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9411:31: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9433:31: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9433:43: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9609:18: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9609:31: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9709:18: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9709:31: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9736:18: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:9736:31: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:10245:21: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:10396:21: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:10486:21: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:10593:16: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:10642:11: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:13667:21: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:13667:47: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:14594:18: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:14759:11: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:14773:11: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:14775:16: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:14821:18: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:15070:20: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:15250:21: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:15449:16: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:15450:16: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:15451:19: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16141:10: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16193:17: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16193:33: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16311:14: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16348:35: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16355:22: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16377:66: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16417:32: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16421:31: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:16422:34: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:20383:50: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:20383:83: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:20383:123: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:21708:28: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:22084:16: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
../../nuklear.h:28043:32: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
```

Example warning sites:
```
../../nuklear.h: In function 'nk_atan2':
../../nuklear.h:6546:10: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
6546 | if(y == 0.0 && x == 0.0) return 0.0f;
```

```
../../nuklear.h: In function 'nk_panel_end':
../../nuklear.h:20383:50: warning: comparing floating-point with '==' or '!=' is unsafe [-Wfloat-equal]
20383 | int has_input = ctx->input.mouse.delta.x != 0 || ctx->input.mouse.delta.y != 0 || ctx->input.mouse.scroll_delta.y != 0;
```

Could it be that hard to reproduce anomalies of sliders, scroll bars may have to do something with these comparisons?

Start in nuklear.h at the warning sites listed in the issue, especially nk_atan2 and nk_panel_end. Reproduce the GCC or Clang -Wfloat-equal warnings and inspect whether the floating-point comparisons correspond to slider or scrollbar anomalies. Done should establish whether these comparisons cause the reported behavior and identify the affected sites.

Written by the indexing model from the issue text.