Add a simple way to version tag payloads

[fjtc]

Add a simple way to version tag payloads. The current suggestion is to format the payload with a version prefix and a way to put the actual payload after that.

[fjtc]

This implementation will use generics as a way to simplify its usage.

[monoman]

In C#, most payloads derive from VersionedPayload, which assumes the first field (Version) is an unsigned short int (16 bits) tag (id 5), with the version number. And this value is used to direct the serialization/deserialization of the remaining fields.
Different from your implementation Version is a tag itself and occupies 3 bytes. This was done to be more compatible in parsing alongside previously unversioned payloads.