make sure the outgoing bitrate stat drops to 0 when last listener detaches from fh
make sure the passthrough stream is accounted for, or else lag will trigger for listeners
trap for the odd case of no mpeg details being set up, prevents null deref crash
Add ${mount} expansion to intro file, on-connect and fallback tag values

While wildcard support in mount-name can be useful, it was limiting for applying settings
for the above where you want to determine the actual result based on the requested mount, now
the ${mount} can be used to apply the option to the values

eg

<mount>
   <mount-name>/live-*</mount-name>
   <intro>/intro/${mount}.mp3</intro>
   <fallback-mount>/backup/${mount}</fallback-mount>
</mount>

With the above, the block can match

/live-64  using intro /intro/live-64.mp3, fallback to /backup/live-64
/live-128 using intro /intro/live-128.mp3, fallback to /backup/live-128

The ${mount} is the mountpoint without the initial / so that you can concatenate the name onto
another such as /backup-${mount} becomes /backup-live-64
in cases with privileged ports over reload, this test was reporting a false error