- UPnP defaults to on - I didn't do all this for nothing

- Set Status to OK for local public addresses or UPnP port open
- Allow UDP address changes after we transition to firewalled
- Have NTCP start reporting reachability status, this will
  get OK on the console more often and mask UDP problems,
  which might be good or bad...
- Fix UDP port configuration
- Reword and rearrange configuration options again
- Rearrange configuration help
- More right-alignment on config
- Prevent Concurrent modification exception in UPnP
- UPnP HTML output tweaks - remove "plugin" references
- Move UDP message failed log from WARN to INFO
- Short-circuit message history call in UDP