SpacecraftState Date mismatch
When using a FixedRate attitude law in a propagator, the propagate method will throw an exception because the orbit date and attitude date do not match exactly. The dates are off by less than a femtosecond.
I propose to fix by adding a tolerance to the date comparison in SpacecraftState. I think 100 ns will be sufficient to ensure sub-mm agreement at orbital velocities.
(from redmine: issue id 167, created on 2014-03-07, closed on 2015-01-12)