Changes

Add RCS stats to the stage stats display

Works fairly similarly to KER, but knows about fuel flow and RCS
staging activation.  RCS drop tanks in stock shouldn't work correctly
at this point, need to have some kind of logic to quit the RCS
simulation early if all of the drainable RCS resources have been
drained from the parts that would drop after the next staging
activation.

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>
 (commit: 45710d6)