Add :add-artist
Sort :add-artist results comparing albums names

Solves the problem where a prolific artist releases more than one album
in a year; previously, tracks from those albums were interleaved.
Cleanup a bunch of HLint warnings
Fix hlint pragma syntax

Clean missed warnings up
Add ZSH completion script

Exploit ZSH's bash completion compatibility mode
rather than write a proper zsh completion script.
Merge pull request #64 from joachifm/zsh-completion

Add ZSH completion script
Do not depend on base-compat, update README
Set github pointers to new upstream
ncursesw: declare dependency on c2hs
Recognize '\DEL' as backspace