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