#15 Support of RFC 3455

[Bastien Bailly]

With this patch Sofia-SIP stack will be able to handle SIP headers of RFC 3455 'Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the 3rd-Generation Partnership Project (3GPP)'
Following headers should be supported:
P-Associated-URI
P-Called-Party-ID
P-Visited-Network-ID
P-Access-Network-Info
P-Charging-Function-Addresses
P-Charging-Vector

To use these headers sip_update_default_mclass(sip_extend_mclass(NULL)); must be called before entity creation.

[Bastien Bailly]

Patch for support of rfc 3455 (updated)

[Bastien Bailly]

I had a little correction on P-Charging-Vector decoding