Every search reply we sent carried no bitrate or duration, so our files
failed every bitrate filter in other clients and sorted last in
SoulseekQt, whatever their quality. The share scan now reads each MP3's
first frame header (and Xing block for variable bitrate) and each FLAC's
STREAMINFO, advertising bitrate, duration, VBR, sample rate and bit
depth as far as the format gives them; other files stay bare. Only the
file's head is read, no crate is needed, and a file that does not parse
is shared without attributes rather than skipped.