gen-art-34

- ".., it then sends…" -> ".., it then MUST send …".
- "In no event does an attempt to reestablish connectivity with a lost
  neighbor allow the peer to remain in the neighbor table." ->
  "In the case of an attempt to reestablish connectivity with a lost
  neighbor, the peer MUST be removed from the neighbor table."
- "should"" -> ""SHOULD" (3 cases)
- "use Pings"" -> "MUST use Pings"
Merge pull request #165 from petithug/gen-art-34

Gen-ART 34