rgbds 0.1.0 (new formula)

Game Boy assembler and linker. I do a custom install because the makefile does funky stuff with the man path that causes 'make install' to fail.

https://github.com/bentley/rgbds
We could use a patch or inreplace to set PREFIX and MANPREFIX correctly. Ideally he'd have `PREFIX?=/usr/local` in the Makefile which would use a `PREFIX` environment variable we set or fall back to his version as a default. Could you try and work on that and submit it upstream? Thanks!