Ore Layers

All this time the ores were not in the other repo because .xcf was in
the .gitignore. Even though I made them, they did not show up in the
repo, of course. Silly me!
Ore guide rewritten for clarity
Justin_a's batch image overlay script

Also included is an updated tinkers greyscale tool library and the
overlays used to create the Tinkers Tools V2 set.
Add .gitignore

- Remove Thumbs and other misc files