This fixes a bug when libsamplerate returns an empty buffer for a very
small input buffer.  The caller thinks this is an error, bug there is
no GError object.

This method is too complex for inlining.

This function is too complex for being inlined everywhere.

Reduce the overhead.  Most buffers used by MPD are around 2 to 4 kB.
8 kB seems large enough to keep heap fragmentation low.

Additionally, this patch fixes an off-by-one error in the alignment
formula.

This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

When I implemented the pcm_buffer library, I forgot to set the new
buffer size.  This caused a new allocation in each pcm_buffer_get(),
fortunately no memory was leaked.

This library allocates temporary buffers for storing PCM conversion
results.  It should replace all those "static" buffer variables which
are racy and never freed.