Terminate simulation after failed allocations

[laprej]

Copied from #22:

I would love for there to be an option to kill the simulation after N consecutive failed "allocation" attempts. E.g., last evening before I left I set up a sweep of ~700 simulations, the 10th of which entered an infinite "buffers not available" loop I then killed this morning. A "g_tw_max_consec_nobuf_ct" or something (defaulting to ULONG_MAX or similar) would do the trick, along with a bit of extra logic to track and reset the failure count accordingly. Basically, an "opt-in" workaround for issue #6.