- rename ha_mgr to recovd

- rename ha_mgr to recovd
- rename connmgr_obd to recovd_obd
- pack fids as part of body_pack/body_unpack
- do body_pack/unpack for both requests and replies
- clean up 3 different groups of constants:
 - PTL_RPC_MSG_ERR/REQUEST -- into _idl: part of lustre_msg
 - PTL_RPC_FL_{TIMEOUT,REPLY...,} -- bitmask part of request->rq_flags
      will control the state machine for recovery somewhat
 - PTL_RPC_TYPE_REQUEST/REPLY -- request->rq_type:
      to determine what kind of packet is being sent
- ptlrpc_error: set the msg type field to an error message, otherwise
  the reply body is accidentally unpacked
- add a c_level field to the connection: the level will control what
  RPC's will go out during recovery and which ones are held up until
  recovery completes. This will be compared with an rq_level field
  (still to be added).
- mdc_connect further finished:
 - it gets the fid of ROOT on the MDS and
 - llite/super.c now uses that as the root inode. Didn't see major
   havoc.
 - the mds has a mds_rootfid field accordingly. This is set in
   mds_prep.