Error reporting for inheritance sims.

This is a patch release that includes some helpful error reporting for inheritance simulations. In particular, it produces a helpful notification when the simulation terminates because the reaction rates have dropped to zero and there is no simulation end time (the simulation time effectively reaches infinity).

As usual, the standalone version is MASTER-A.B.C.zip while the BEAST 2 package (install via BEAUti's package manager) is MASTER.package.vA.B.C.zip.