- add $os to ir/ast.d
	- add alias in lib/ffi for $os
	- add test for ffi.os
Merge branch 'master' into ffi.os
	- switch ffi.os to use string from util/os.d
Merge pull request #95 from teebrz/ffi.os

ffi.os
Merge branch 'master' into font-fix

Conflicts:
	source/lib/ffi.js
	source/tests/08-lib/ffi.js