Request/Response json: s/message_(headers|body)/$1/g
Request_Line json: s/Request_URI/URI/g
_SIP_URI json: s/uri_parameters/params/g
sipuriBuild json: flatten userinfo/hostport

sipuriBuild() returns an object with 'user', 'password', 'host', and 'port'
properties, instead of hiding them behind 'userinfo' and 'hostport'.

Note: this breaks serialization if the sipuriBuild() output json is modified.
media_type json: remove 'm_' prefix
CSeq json: simplify property names

sequenceNumber -> number
requestMethod -> method
output json: use 'parameters' instead of *params
name_addr json: s/display_name/name/g
via_parm/sent_protocol json: remove prefixes
accept_range/language json: remove *range prefix