The server can now send data about the mod to the client

Server-side mods should be able to introduce new materials, monsters and so on. For this to work, the client needs to get some data from the mod after connecting.

I'm still exploring how mods would actually work (for now it's a simple XAML-based deserialization mechanism).
Bugfix: Channels took the wrong lock on their player entity
Let there be a cube
Added a C++ launcher

* This forces NVIDIA Optimus switching to use the GPU on laptops.
* This will later allow us to inject optimized C++ data structures more cleanly.
Chunk data transmission