instrunctions to fetch'n'merge from cloned repo
Fix. Allow case-insentivity in SIP grammar, when corresponds

Make header values, parameter names and parameter values case-insensitive
Merge remote-tracking branch 'upstream/master'
 * SIP DTMF via INFO / grant media access once

 Implementing DTMF signalling via SIP INFO packets,
 this works if you're calling through a third party
 (eg a pbx) that will translate your signal into
 a proper RTP Payload for DTMF Digits (RFC 2833).

 Grant access to media once per session. This way
 user hasn't to give permission for every call.
 We set a fake session in the beginning and use
 the stream object for all other session we will use
 for future calls.