media formats: fix ref leak of peer for mwi subscription

Holding a reference to the peer during mwi subscriptions
resulted in a circular reference because the final event
message would not be sent until destruction of the peer.

Instead, pass the name of the peer to the event callback
so that it can fail gracefully after the peer has gone.

ASTERISK-23959
Review: https://reviewboard.asterisk.org/r/3754/



git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@418636 f38db490-d61c-443f-a65b-d21fe96a405b
func_uri: URIENCODE/URIDECODE - allow empty strings as argument

Previously these two dialplan functions would issue warnings and
return failure when an empty string is used as the argument. Now
they will not issue a warning and will successfully return an
empty string.

ASTERISK-23911 #close
Reported by: Matt Jordan
Review: https://reviewboard.asterisk.org/r/3745/
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Merged revisions 418641 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 418649 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/12@418650 f38db490-d61c-443f-a65b-d21fe96a405b