FS-2731 significantly reworked version of Emmanuel's patch to allow subscribing and notifying for the as-feature-event events.  we still need a module to handle the FS events for this automatically... coming soon to a repository near you

* Rename option ringback-during-collect to immediate-ringback
* Allow regular ringback tone with immediate-ringback, not just a wav file
* Do not request full frame of data, just packet_len which is what we receive per IO interval
* Ignore user data when playing ringback tone

Split naming of T.81/T.42 type JPEG from normal JPEG. This is in preparation
for allowing the selective output of normal JPEG (like most people want)
and the T.81/T.42 type you might want for forwarding as T.37

tables.

This reverts commit c21f65ac.