The CLI would often have temporary screen corruption.  This reworks
several things to correct that issue, although it looks like the
ultimate cause was drawing to the screen while in the middle of
waiting on a VT100 ESC keycode sequence.

* Rearchitected all screen drawing to run in a single thread.  Now
  call set_screen_dirty() instead of draw_screen()
* Added a lock on accessing the various Log buffers, preventing
  changes to the buffer in the middle of a redraw
* Modified key reading logic when ESC character is received.  Now
  uses a 1 second timeout if no subsequent keycodes are sent

Curses throws exceptions in some cases during get_wch(), such as
when you Ctrl+Z suspend the CLI the resume the process.

Also moved Ctrl+C processing into this exception handler.