core: added AmUriParser functions to bring inline with 1.6

relevant commits:
28dd1a8 added method to print canonical URI
e2cb88c c/f: return value of skip_name() is signed, size_t is not.
01c4e1c sbc: first REGISTER cache draft
c39cd27 generic request forwarding (WIP 2)
786a59a added add_param_to_param_list(), add_user_param() and print() methods
e9f988c b/f: parsing issue in AmUriParser when dealing with parameters in the username part (bug # 81)
01b2796 sbc: added support for R-URI host modification
20d7bef b/f: fix display name replacements, $fn/$tn etc

plus tests
core: AmUriParser: fix headers in nameaddr_str, added parse_nameaddr function alias
utils: added URL_encode and URL_decode functions
sbc: fix call transfers with Replaces through SBC

Replaces header is fixed in either Replaces of INVITE or of REFER
messages. New sbc profile options:
fix_replaces_inv=[yes|no]
fix_replaces_ref=[yes|no]
Merge remote-tracking branch 'frafos/sayer/1.4-spce3.0'