These tags are used to modify the Contact header generated by the stack in
the nua_handle_contact_by_via() header. Currently, the tags only affect
Contact header generated for registration.

Updated internal outbound interface in order to make use of the new features.

darcs-hash:20060913135519-65a35-6531f086bb5e7f454e568ebb144768163a6bb4c9.gz

darcs-hash:20060517130101-65a35-cf0e5af13bf73fa8b488dda4ea79ae2d23029197.gz

darcs-hash:20060510202847-65a35-4bf4f0b5bb709680fc70544dddd52bf3420efcc3.gz

Added outbound.c, outbound.h.

darcs-hash:20060510184252-65a35-4718eb68e874fce9da70cc6746479a99acaccbd6.gz