This version supports keys, in theory at least, although it is not incredibly well-tested yet. It understands abc K: directives; also you can write any old gnarly key signature using this syntax in the abc file:
; The key of D major...
keysig G# C#
; The key of WTF?
keysig G# Ab Cb
Also c/ == c/2 now, as specified in the abc standard.