Changes

JOGL/OSX: Properly utilize NSOpenGLContext update() via ContextUpdater, which only holds the 'update' state now.

Avoid calling updater() for every makeCurrent(), but if view's frame has changed only.
This solves the pixel flickering experienced on OSX.

- GLContextImpl:update() -> drawableUpdatedNotify() w/ comments

- ContextUpdater holds context, view, old view frame and the update state.
  It doesn't issue NSOpenGLContext update() by itself, but allows querying and clearing the update flag.

- MacOSXOnscreenCGLContext impl drawableUpdatedNotify()
   - register via ContextUpdater, and use it if available.

GLCanvas / GLWindow: Change 'manual' resize/repaint animation filter

We not only shall skip windowing system triggered repaint if another animation thread
is running, but also if the current thread is the animator thread.
This keeps the animator intervals stable while resizing.

NEWT: Filter Window focusChanged() and visibleChanged() [test if value changed]

NEWT/OSX: Fix resize behavior / Cleanup coordinate transormation (client-space/top-level, child/parent)

At resizing a perent window w/ a NEWT OSX child,
the window position needs to be updated since it's absolute.

Re-adding sending *Changed notifications via the appropriate WindowImpl methods.
Turns out they are missing in some parent/child situations (fullscreen for example).

Native getLocationOnScreen0(..) queries totalHeight by it's own to have correct values.

TestParenting03AWT: Add manual code to disable 2nd GLWindow for internal testing (def.: enabled)