option to show full paths for fileslower and related tools

I just used fileslower for the first time, it's really a cool tool. Thanks for that already!

But looking at the results, it leaves me guessing as to what file is actually being referenced:

```

Tracing sync read/writes slower than 100 ms
TIME(s) COMM TID D BYTES LAT(ms) FILENAME
3.215 akonadi_follow 8034 R 16384 324.60 agent_config_akonadi_followup...
3.218 akonadi_indexi 8044 R 16384 330.60 agent_config_akonadi_indexing...
3.270 akonadi_ical_r 8040 R 16384 379.21 agent_config_akonadi_ical_res...
3.338 akonadi_akonot 8029 R 16384 394.43 agent_config_akonadi_akonotes...
3.350 akonadi_maildi 8046 R 16384 457.47 agent_config_akonadi_maildisp...
3.354 akonadi_contac 8033 R 16384 419.19 agent_config_akonadi_contacts...
3.354 akonadi_vcard_ 8052 R 16384 413.45 agent_config_akonadi_vcard_re...
3.354 akonadi_maildi 8045 R 16384 404.17 agent_config_akonadi_maildir_...
3.367 akonadi_akonot 8028 R 16384 426.73 agent_config_akonadi_akonotes...
3.382 akonadi_akonot 8031 R 16384 487.54 agent_config_akonadi_akonotes...
3.405 akonadi_migrat 8048 R 16384 401.60 akonadi-migrationrc
3.418 akonadi_indexi 8044 R 16384 199.96 agent_config_akonadi_indexing...
3.418 akonadi_ical_r 8040 R 16384 108.69 akonadi_ical_resource_0rc
3.418 akonadi_notes_ 8050 R 16384 404.33 akonadi_notes_agentrc
3.425 akonadi_akonot 8030 R 16384 410.83 akonadi_akonotes_resource_2rc
3.454 akonadi_maildi 8046 R 16384 103.39 agent_config_akonadi_maildisp...
3.583 akonadi_ical_r 8040 R 524288 111.20 std.ics
3.620 akonadi_akonot 8031 R 16384 135.59 akonadi_akonotes_resource_3rc
3.637 akonadi_vcard_ 8052 R 16384 157.05 Default Address Bookrc
3.783 akonadi_maildi 8046 R 16384 272.56 specialmailcollectionsrc
3.800 akonadi_akonot 8029 R 16384 225.03 1343311121.R370.milian-kdab2
3.898 akonadi_vcard_ 8052 R 524288 261.01 std.vcf
3.898 akonadi_akonot 8028 R 16384 430.36 akonadi_akonotes_resource_0rc
3.933 akonadi_akonot 8029 R 16384 123.05 types
3.961 akonadi_indexi 8044 R 16384 457.26 baloorc
6.712 kmail 8185 R 4096 115.27 machine-id
```

I'd like to request two options to improve this situation:

- a way to increase the filename limit, such that I at least see the full filename instead of e.g. `agent_config_akonadi_akonotes...`
- an option to print the full path, instead of just the filename

If you guide me as to what would be required to implement this, I'd be willing to provide a patch. Just increasing the `DNAME_INLINE_LEN` in `fileslower.py` doesn't seem to produce correct results ;-)

Cheers

Start with fileslower.py and inspect how DNAME_INLINE_LEN affects the displayed filename and how related tools format file information. Determine the existing output and option handling before implementing configurable filename length and full-path output; done means both requested forms display correctly.

Written by the indexing model from the issue text.