Changes

Bug 1214: Fix Deadlock in screenPositionChanged(..); Use
screenPositionChanged(..) in size[Screen]PosInsetsChanged(..) on OSX;
Cleanup OSX Code
- Fix Deadlock in screenPositionChanged(..)
 Defer requires to spawn whole child-window action to another thread
 since we may come from native 'NewtWindow::windowDidMove()' on
MainThread.
- Use screenPositionChanged(..) in size[Screen]PosInsetsChanged(..) on
OSX
 Move callback WindowImpl::sizePosInsetsChanged(..)
 to OSX's WindowDriver::sizeScreenPosInsetsChanged(..),
 since we need to use screenPositionChanged(..) to calculate
 child window relative position to parent.
 I.e. we receive the location on screen.
- Cleanup OSX Code
 - Native JNI entries shall handle NULL windowHandle -> return
  - Clarify usage of 'getWindowHandle()' and use 'isNativeValid()'
   if appropriate.
  - Don't re-use cached getWindowHandle()
   for non-blocking off-thread actions, since handle may become invalid.
  - Clarify getLocationOnScreen*(..) implementation code,
   i.e. separate getLocationOnScreenByParent(..) semantics.

Bug 1188: Fix setMaximized(..) isReconfigureMaskSupported(..) query
setMaximized(..) isReconfigureMaskSupported(..) was using the state
bit-number instead of the state bit-mask!
Fixed.

Bug 1223 OSX: GLWindow loses focus after maximizing - Analysis
TestGearsES2NEWT reacts on key-press 'n', opening another GLWindow.
Procedure:
[1] Pressing 'n' (2nd GLWindow) and manual re-focus 1st GLWindow
[2] Pressing 'm' (single, alt, shift) on 1st GLWindow maximizes it
   Focus is still on 1st GLWindow!
[3] Pressing ctrl-m un-maximizes ..
   Focus is still on 1st GLWindow!

Adapt Test NApplet HTML Pages to NEWTDemoListener (all key-actions)

NEWTDemoListener: Fix 'v' modifier collision of ctrl, use shift.

Bug 1222 - NEWT OSX: setAlwaysOnTop() and setAlwaysOnBottom() not
working
- The NSWindow level must be set at window creation
- Levels are
 - aontop: kCGMaximumWindowLevel
 - aonbottom: kCGDesktopIconWindowLevel (w/ input)
 - normal: NSNormalWindowLevel
- Hence we need to recreate the NSWindow if toggling the state,
 similar to opaque .. etc.