[sr-dev] list of things to do in branch_route

[Juha Heinanen]

in order to avoid more surprises with branch routes, here is complete
list of things that i need to be able to do in branch_route:

- call functions is_local() from modules_s/domain, is_method() and
  append_hf() from modules_k/textops, verify_destination() from
  modules/peering (uses radius), add_rr_param() from modules_k/rr,
  fix_nated_sdp() from modules_k/nathelper, use_media_proxy() from
  modules_k/mediaproxy, t_on_reply() from modules/tm,
  allow_source_address() from modules_k/permissions

- set $var pvs

- test flags, bflags, and gflags as well as set bflags

- test $avp pvs using is_avp_set and operators

- set $du

they are come from my working k configuration.  hopefully the last one
is the only one that is not supported yet.

-- juha