Fix compressed graphics and filestructure

-No more /lz folders.

-Fixed some lz files that didn't have terminators
  An extraction error caused some lz files in gfx/misc/ to lack
  terminators. These slipped through the cracks since they were
  surrounded by incbins calculated from the filesize, and the
  original decompression was done from the baserom, where
  terminators were intact.

  There might be more offending lz files.
Finish off make target for png generation

Now any existing lz files are converted to 2bpp, and all 2bpp files
are converted to png.