Implemented RDP channel support
Fixes #14 (closed): Basic RDP channel support for modern graphics pipeline and video redirection support added.
- Fixes resource cleanup on session disconnect (use post_disconnect callback for that)
- Registers channel event listeners
- Initializes graphics pipeline and video redirection channel (#2 (closed))
Not part of this merge:
With this applied #7 (closed) can be refactored and split in multiple files.