The nrun conversion was slightly incorrect in how it stopped when an
exception occurred. We still set cpu.asregs.exception, but nothing
was checking it anymore. Convert all of that to sim_engine_halt.
To keep things from regressing again, add a basic testsuite too.
We want people to stop using the run.c frontend, but it's hard to notice
when it's still set as the default. Lets flip things so nrun.c is the
default, and users of run.c will get an error by default. We turn that
error into a warning for existing sims so we don't break them -- this is
mostly meant for people starting new ports.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
