Removed the icon color blend operations from human's update_icons().
Changed all the hair/facial_hair/eye sprites to use a white base.
Changed the preview screen, in the preference menu, to use ICON_MULTIPLY to be able to use the new white sprites.
Removed the unused and broken cloaking item.
Ninjas now use the alpha variable, removed most of the checks for it.
Updated the documentation a bit.
Added some helper procs for later.