Dynamic Flavour Text

Suggested here: http://baystation12.net/forums/viewtopic.php?f=5&t=10913
There are 18 in favor (counting both options) and 3 opposed.

Changes:
* Updated body_parts_covered for everything
* Added a text helper to do text previewing (good for flavour text and character records, figured it would reduce code copypaste)
* Updated preferences and the IG verb GUI for setting flavour text to let you set flavour text for the head, face, eyes, torso, arms, hands, legs, feet, and general (shown regardless).
* Added face and eyes bitflags for body_parts_covered
* Examining shows only the flavour text of bodyparts not covered by clothes
* Fixed an issue where detective fiber/prints coverage checks were using wrong, hardcoded values instead of bitflags
* Updated the changelog

I'm not a super proficient coder, so if you have any suggestions to improve this (even if unnecessary or petty) I would still love to hear them.
For future reference, when adding new flags, just put then in the end, that way you won't have to redefine all of previous ones.