just a start
Made a macro to turn off logging. Added a check to see whether time is moving backwards, which can happen if hazards are negative on input.
There was a bug in sampling exponential distributions. Really. But only for the competing-processes version of the propagator, which is the slow one.
checking that the hazard is positive for the exponential distribution.
This fixes a very important bug where tokens that were moved with Move<0,0> didn't get registered as having changed the state.
Removed sirexp because it left, but the modifications made here are good. Less logging and fixed one crucial bug in reporting modified places.