Adding Slow and Pause to drone testing

[Ian S]

As requested, I'm cutting up my other post into individual sections for easier commenting.

It would be really useful to be able to slow the speed down and even pause it in the drone test mode. When trying to debug some autonomous circuitry I was building I found that when it went wrong and the ship flew apart, it was all to small and fast for me to be able to see the circuits indicator lights and without that that I couldn't work out where the failure was coming from.

[Lurkily]

Not 100% sure on this one.  I only rarely rely on circuit observations, experimentation with input/output control can often be used to reveal problems when the sequence goes too fast to follow, and unless the engine supports a variable timescale already, there are a lot of other things I'd like to see dev time spent on first.  Besides, a lot of logic responses are an instant cascade of outputs, inputs, and results.