Changes

Add RCS Ullage Time to FuelStats

Should be accurate amount of time required to go from zero stability
to 100% reliable ignition.

Also resets the ignition stability checks in the ThrustController
to 0.996 which is what RF rounds off to 100% stable / no failures.

This will make "prevent unstable ignitions" even more incompatible
with sounding rockets, but it was already quite incompatible and was
turned off by default.
 (commit: e97bc4e)