- Rewrite find_user_host() to use split_nuh()

- First pass at s_conf.c cleanup for attach clients
- attach_conf() is gone replaced with attach_iline()
  Clients/servers have one single I line "attached", i.e. the confs
  list is gone.
- Add attach_leaf_hub()
  Add a leaf or hub mask to the given server, ->serv must exist
  since there can be a list of hub masks and leaf masks, this continues
  to be a dlink list
- Removed redundant find_conf_exact()
  This function can be replaced in all cases with find_exact_name_conf()
  notably because all find_conf_exact did differently was count whether
  an oper conf would cause an already connected client to exceed class limits.
- oper_up() now takes an extra conf pointer pointing to the found
  oper conf, the oper flags are set in the client->iline as necessary
  in oper_up()
- Cleaned up more prototypes that should have been moved from s_conf.h
  to parse_aline.h notably. find_kill() and find_gkill()
- m_stats.c needs more cleanup since memory in attached "confs" is now
  not counted. This should be replaced with iline memory count and
  hub/leaf confs memory count.