version 3: unlock conditions

version 3:
-cleaned up the format of the skin folder (skin.gml files are now located in the named folders with the sprites)
-added a savefile feature (like in hardmod) where all options are saved between sessions
-added /idpdtb :lets the idpd skins (fish,eyes,crystal) use previously unused sprites when they have thronebutt
-added unlock conditions to each skin, some people like to play ntt with their incomplete nt file (may need ntt9927+)
-unlocked skins are stored with the save file
-added /restart :locks all skins (cant lock the ntt built in skins. yv c, robot c, skeleton b)
-added /unlockall :unlocks all skins
-fixed an issue with the icons mod in current beta versions of ntt (9927)