audioconvert: If we have to lose precision, try to lose as less precision as possible

https://bugzilla.gnome.org/show_bug.cgi?id=706624
rtcpbuffer: calculate FB packet length correctly
gio: make better use of the cached buffer

When playing mp3 files from a smb server, we get 64k read requests
that mostly overlap.  Without using the cache to partially satisfy
these, we send these requests straight to the server, resulting in
a lot more network traffic than necessary.

https://bugzilla.gnome.org/show_bug.cgi?id=705415
gio: fix printf format compiler warning
rtcpbuffer: do additional packet checks

Check the packet size and avoid crashing on malformed packets.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=655727
Release 1.0.10
typefinding: don't detect mp3 based on just a few bits

Remove dodgy code that detects mp3 with as little as
a valid frame sync at the beginning. This was only used
in some unit tests in -good where there were only a few
bytes after the id3 tag. We now require at least two
frame headers.

Fixes mis-dection of text files with UTF-16 LE BOM as mp3.

https://bugzilla.gnome.org/show_bug.cgi?id=681368