Update() now accepts a frames parameter which can control the number of frames updated.
-1 will update until shutdown.
The watchdog updating moves above the maintc recalculation for any required sleep since it should be accounted for within the frame.
I thought that I had implemented this but must have accidentally removed it.
Adds a regression test to detect if this happens again.
Temporarily disables automatic landing of NPC at a target. Will be fixed presently.