Removed the catches for std:exceptions and unknown exceptions. The best way
I found to provide a clue to where the exception comes from is to allow the
handler for unhandled exceptions execute. This is std::terminate which calls
abort and trips a SIGABRT. I added a signal handler for SIGABRT which like
SIGSEGV, we can print a stack trace or attach a debugger to the process before
exiting. The stack trace print is on by default. By default the signal
handler is on, stack trace is on, debugger is off.
refs #220
03d6105c6c