Kaiju Engine (issue #33) - Cleanup initial Win32 window code

Adding a fatal message to be read from the caller of the window creation. If a fatal is returned from window create, then it will panic with the message. I've also better wrapped the shared memory into the InputEvent structure so that it can be written to without the need of memcpy. I also updated X11 to use the helper methods created for the shared memory.

https://github.com/KaijuEngine/kaiju/pull/34