Audio fixes

after scanning the forums for user reports, here are some more fixes:

- fix paplayer's flac codec, it did not handle 7 and 8 channels
- fix hang of ActiveAE if stream provided data which did not fit exactly in a multiple of framesize
- another fix remapping to sink format with more than 8 channels. ffmpeg has no default layout for this case.

for the protocol: thanks to @fritsch for working with me on this