add i3-msg like command line functionality

[neonpixii]

It would be helpful for there to be a way to send commands to nog via commandline calls, similar to i3-msg is for i3wm. The specific use case I have would be for letting talon voice (accessibility software I use) control nog directly without having to go through key presses.

[TimUntersberger]

I was in the process of completely rewritten nog here. It is almost done, but has no documentation. For now you could try it out as it has its own cli, which can execute any lua code in the scope of the nog runtime.