Merge pull request #106 from yenatch/master

Update gfx.py with things.
add swap~ files to .gitignore
Merge pull request #107 from yenatch/master

2bpp to png and png to 2bpp
use pypng as a dependency
Merge pull request #108 from yenatch/master

png->lz and palettes
Merge pull request #109 from yenatch/master

png export fixes
Last map header label