Outbound proxies automatic config
UDP "connection" first support
STUN rework in udp transport
Keep Alive in tcp transport
UDP support in nksip_transport_srv
UDP transport rework in nksip_transport
Start ping on specific response
Add default 'outbound' support
Default times for keep alive
Time Alive support for UDP, TCP/TLS and SCTP
Doc updates
Refactorization of Contact processing in responses
'outbound_reg_id' renamed to 'reg_id'
Fix error in nksip_transport_udp
Create flow on inbound
Refactorization of automatic Contact generation
Minor updates
UDP connection rework
First outbound test
UDP messaging routing rework

Now UDP transport simulates somehow the notion of a 'connection'.

Each time a mensaje is sent or received, a connection is set up to that remote ip and port, and a instance of 'nksip_transport_udp_conn' is started.