Refine GL[Auto]Drawable 'realized' state in API doc, and relax it's realized requirement in GL[Offscreen]AutoDrawableDelegate*

Compatible w/ 'before'.

TODO: Contemplate about GLDrawableFactory.createOffscreenAutoDrawable(..) whether it:
  - should better return an unrealized [auto]drawable
  - or adding another API method for such case

  Goal: Allow passing vector of [device/context/..] for use cases
        such as re-using an onscreen destructed surface and on-/offscreen hopping.
Animator: API doc cleanup, isPaused()==true if drawablesEmpty (Animator == FPSAnimator behavior), resume after add ifPaused()

- GLAnimatorControl: Refine API doc

- Animator.run():
  - if( drawablesEmpt) { pausedIssued = true; } - Same behavior as FPSAnimator

- AnimatorBase.add(..)
  - consider paused case if no drawablesEmpty, i.e. if ( isPaused() ) { resume(); }
Fix misc API docs ..
GLDrawableHelper.invoke: If drawable is !realized -> deferred execution
Fix regression of commit b738983638703bb721ee4c9820c8ef43e2252e73, possible 'pulling' display's device - check references