electro_ball.png needed to preserve one whitespace tile which tools/gfx would normally remove. Preserving a list of tile indexes has been added as a general feature to tools/gfx.
sgb_border.bin needed to remove the 20x18 center area of $00 bytes. This is achievable with the standard tr utility.
I have no idea why this was a thing (do people store this repo on FAT32
flash drives or something?), but quite a bit of files had a permission
of 755. This isn't really a problem, but it's inconsistent and weird.
This is just a pet-peeve of mine, but if you're going to have half of
the repo filled with clean PNGs, and only have some with this metadata,
might as well clean it all right up.
