More x11 terminal fixes

[Dima K. <gn...@di...>]

I'm starting a new thread to talk strictly about regressions in and fixes to the
patch I sent last month to get x11 aspect ratios to work right. That thread is
"[PATCH] x11 terminal respects the requested aspect ratio".

I've discovered some more issues, and addressed them in the attached patch.
These are

- with -replotonresize, two replots were happening when a window was resized:
  the initial outboard-only even-aspect-ratio one, and then the full replot. It
  was inefficient and unnecessary to do the first replot in this case, so I no
  longer do it with -replotonresize

- This replot becomes essential if the inboard driver is killed, but the plot is
  still up because of -persist. This replot is thus always done when the
  inboard-outboard pipe is broken

- When the inboard driver is killed, the mouse-over coordinates were not
  computed correctly. Fixed.

dima