Face flag body part coverage changes.

Created by: ComicIronic

Removed the HEADCOVERSEYES, MASKCOVERSEYES, GLASSESCOVERSEYES, HEADCOVERSMOUTH, and MASKCOVERSMOUTH flags. Added the EYES, EARS, and MOUTH flags for body_parts_covered. Added a proc for getting the item giving a flag, instead of just checking that it's there. Made borers check for the EARS flag, instead of using HIDEEARS. More code now uses either get_body_part_coverage or check_body_part_coverage, instead of snowflaking.

Next on the chopping block are BLOCKHAIR and BLOCKHEADHAIR, which are going to be shoved into flags_inv.