only do one block when we are called...

flac.py:
add the support for returning the results of one block or up to
n samples...  This should help prevent some of the coping that
goes w/ combining strings, though it may increase call overhead..

add usage...

[git-p4: depot-paths = "//depot/": change = 1424]

make decoding faster...  uses about a third of the cpu as the
pure python version did...

[git-p4: depot-paths = "//depot/": change = 1418]

it supports seeking, but only 16bit audio currently...

[git-p4: depot-paths = "//depot/": change = 1411]