Sync with upstream SDL2_gfx 1.0.0 release

Synced with upstream release tarball.

URL: http://www.ferzkopp.net/Software/SDL2_gfx/SDL2_gfx-1.0.0.tar.gz
md5sum: f008cc117cb901aec6bf5c2f0b11f7ea
sha1sum: 6b83f57a62a3d2a3850a56902a008d801c799ff8
[nemo] Package upstream 1.0.0 release of SDL2_gfx

The previous in-development version had version 2.0.0, we're now
reverting back to 1.0.0 to be in sync of what upstream thinks the
version should be.