Protobuf-net: AofL Fork

This is a fork of Protobuf.NET library used by Age of Learning.

academy branch continues release r668 with the following fixes:

1. Removed forward slash / from the list of supported leading characters for arguments, to support unix-style paths
2. Precompiled does NOT fail anymore if .NET Framework version can't be detected
3. Added support for generic types serialization.

See also: Protobuf.NET Documentation