green.core: make play_wav_file a free function

darcs-hash:20090318103612-b2873-feb0770706e48335f91c38b60b9af46ee1c1d320
Changed way in which AccountManager subscribes to account notifications

Ignore-this: efc74dc06c1137a9a73e7193c32789e0

darcs-hash:20090318105049-1e3d8-d341375bee04a7ab2f3c31ad0af5f8e578a5941b