Changes

TestScreenMode02aNEWT: Incr. wait period, for some reason one older test machine (Linux/Ubuntu) doesn't rotate screen reliably.

Bug 1142 - NEWT: Add support to retrieve the primary MonitorDevice

Support added for
  - Windows
  - X11 XRandR 1.3
  - OSX

Note: Our whole MonitorMode association handling is currently _not_ dynamic.
 - only on Windows we actually use native unique ID,
   which might not change (adapter and monitor idx)

 - On OSX and X11 we simply use indices,
   but if monitor setup changes - they refer to different instances.

In case it is desired to cover dynamic monitor setup change,
we need to address this issue in a new bug entry.