Multiple keys should not share the same trigger cooldown

[tiehuis]

As an example, when pressing the rotate button, it will only fire once and the key requires a release and repress before it fires again.

If multiple keys are assigned to the single rotate action, they all share the same trigger so pressing one after the other while the first is still down will not trigger a rotation. This isn't really ideal behaviour since it doesn't provide any improvement over a single key system.

Extend the internal engine so it is aware of different physical key presses and treats actions seperately based on which input triggered it. We need to ensure we handle the case where someone assigns the same key multiple times to an action. This should be filtered during option parsing.