work on buffer...
work on buffer...

* rename ::buffer-cue and ::buffer-stream to ::buffer-in-stream and ::buffer-out-stream
* derive ::buffer-in-stream and ::buffer-out-stream from ::file-buffer
* define #'file-buffer?
* modify #'buffer-stream-close to work for any ::file-buffer
* remove #'buffer-cue-close. use #'buffer-stream-close instead

brunchboy/overtone,ethancrawford/overtone,pje/overtone,la3lma/overtone,Widea/overtone,rosejn/overtone,mcanthony/overtone,chunseoklee/overtone,craftybones/overtone