Enhancement: Add a instruction that halts the CPU

[ArduinoFan0]

My thinking is that an instruction like stop() could be used to permanently halt the CPU, and stop(3000) would halt it for 3 seconds. But I think the perma stop would be more useful, as stop(3000) is pretty much the same as wait(3000).

Also, I just noticed that the documentation doesn't even mention the wait instruction. Maybe a little update there could benefit nesfab programmers. But wait might be a part of a library, so that might maybe be better suited to "library documentation".

Edit: I just realized that the wait instruction is indeed a part of the nes.fab library, and that it takes frames, not milliseconds. My bad.

[pubby]

Hmm what use case for permanent stop do you see? I'm having trouble thinking of a game or program that would want that. For those that do want it, I reckon a singlewhile true line works already.