When destroying the state, ServerMediaSubsession::deleteStream callbacks
are called but we are already deconfiguring so do not send messages to
change destination (eg. audio is already destroyed so the message wont
be delivered causing warnings like:
```
Receiver audio.sender does not exist.
Receiver audio.sender does not exist.
Warning: Message queue not empty!
```
Currently this is just a dirty fix, rtsp_serv::watch would be better to
pass.
When the client doesn't call TEARDOWN (like ffplay doesn't),
the stream could not have been played until the timeout (given by
`reclamationTestSeconds`). After that (or when TEARDOWN was called),
`BasicRTSPOnlySubsession::deleteStream()` is called allowing the new
stream.
After this change, the stream can be redirected withot explicit TEARDOWN
or timeout.
For audio codecs, we respect its native capitalization of letters, eg.
AAC, speex. So do it also for Opus. This should not affect existing
applications since the Opus name is parsed case-insensitively.
Only exception is SDP (rtpmap) where is usually used lower-case (at
least in rfc7587).
using bound checking variants
Remained last one instance in utils/text.c, that does the checking by
itself and vsnprintf compat using vsprintf, that is not used, anyways.
