Dev Docs: Describe Almost All Remaining P2P Network Messages

* Describes all remaining messages except filterload. Specificially, the
  following messages are described: Addr, Alert, FilterAdd, FilterClear,
  GetAddr, Ping, Pong, Reject, VerAck, and Version

* New makefile test: report broken markdown tables

* Put relevant protocol version changes at the top of all message
  subsections.
Normalize references to protocol versions
Fix a few typos
Merge remote-tracking branch 'saivann/protocolversions' into control-messages
Dev Docs: Prefix Table Rows With Added/Updated Status

Suggested by @saivann (thanks!)
Merge branch 'control-messages' (pull #649)