Improved eyecheck()

Changes flash/welder protection eyecheck() proc from several hard coded  item checks to a /var check for eye covering items, reducing the number of IF statements and allowing greater flexibility as child items can have a different protection level to their parent.

Created a new proc tintcheck()
-Items have a separate tint var to allow for items to protect but not impair, such as space helmets.
-tintcheck() adds these up for eye covering locations
-life.dm uses this new proc when checking to apply the welder overlay instead of hardcoded if statements
Changes the check for blindfolds healing eye damage and making the mob blind to work off tintcheck()
Removed accidentally included mask test item
comments for new defines
Merge pull request #697 from Malkevin/Improved_eyecheck()

Improved eyecheck()