I now always 'exit -1' on error
cleared up --stream option logic

- minor refactoring
- --hardcopy and --stream together now generate a warning and turn off --stream
better handling of non-timer-based replots

Previously I was ALWAYS replotting when triggered, ALWAYS replotting on a timer
and NEVER replotting on domain rollover with --monotonic.

I now have logic to do the right thing in all these cases. I now replot on
domain rollover, unless it's happening too quickly.