Block cmdQueue during script execution

[cartermak]

The rocketSideListen thread should only be able to push FIQ emergency commands to the command queue while the hypervisor thread is executing a script.

[cartermak]

Could achieve this by adding a flag to commands that are pushed by rocketSideListen... it'd be a little inefficiently but perhaps easier than having rocketSideListen need to poll a shared variable or anything like that.

[LyonFoster]

If the buttons are inactive, then rocketSideListen won't be able to add anything to the command queue.