Optimized eggshell hats:

 * Delete png/xml files of recolored eggshells.
 * Made original eggshell hat dyeable (reduce number of shades + desaturate)
 * Add dye string for current eggshell hat (give back its slight blue tint)
 * Add dye strings for the 6 easter 2013 eggshell hats
 * Fix incorrect IDs of orange/dark eggshell hats