[WP7] Bring back NET_4, ugh.
Use SAFE in MessageSerializer
[WP7] Fix WP7 project
Update gitignore
[WP7] Fix GetSimplestName()
[UDP] Always run IPv4

This mainly to fix Mono builds, but it's a pretty safe bet that every OS
that can run Tempest has IPv4 support.
Merge branch 'wp7'