TestScreenMode* Cleanup (reset)

- TestScreenMode01aNEWT and TestScreenMode01dNEWT
  test auto-reset (destroying last Screen ref. reinstates orig MonitorMode)

- Other tests do manual reset.

- Add ant test target 'junit.run.newt.monitormode'
  to test only monitor-mode / fullscreen cases
Revisit Bug 770 and Bug 771: Only use FLAG_IS_FULLSCREEN_SPAN if required; At MonitoMode change, reset fullscreen if FLAG_IS_FULLSCREEN_SPAN is supported.

- Bug 770: Only use FLAG_IS_FULLSCREEN_SPAN if required
  - If X11 WindowDriver _and_ virtual-screen-size > fullscreenViewport,
  - else we still use _NET_WM_STATE_FULLSCREEN on X11!

- Bug 771: At MonitoMode change, reset fullscreen if FLAG_IS_FULLSCREEN_SPAN is supported
  - Since we may still use _NET_WM_STATE_FULLSCREEN on X11:
    - Pause fullscreen at monitorModeChangeNotify(..)
    - Resume fullscreen at monitorModeChanged(..)