Add way to remove devices

[Mause]

Either that, or have cpu.reset remove devices
This is to make testing easier :P

[Deleted user]

It should be an error to add or remove devices after any calls to cycle().

[Mause]

And that should probably be another issue :P

[Mause]

Query: is this needed?
or shall it be relegated as a nicety?

[cassiebeckley]

I don't think it's strictly necessary; especially since it isn't allowed after cycle().

[Mause]

Right then