Bug 718: Windows BITMAP Offscreen Fails w/ GLCaps other than simple RGB888 - Refine Unit Tests ; UITestCase.Snapshot: Add RGBA bits to filename.

Split TestGLAutoDrawableFactoryOffscrnCapsNEWT to
      TestGLAutoDrawableFactoryGL2OffscrnCapsNEWT and TestGLAutoDrawableFactoryES2OffscrnCapsNEWT

TestGLAutoDrawableFactoryGL2OffscrnCapsNEWT contains more 'Bitmap' tests of various caps, w/ snapshots.
*Capabilities: Cleanup string ctor; GLGraphicsConfigurationUtil: Clean getExclusiveWinAttributeBits(..); WGLGLCapabilities: Add PFD2String(..)
Bug 718: Windows BITMAP Offscreen Fails w/ GLCaps other than simple RGB888 - Filter invalid PFD configs

- Filter invalid PFD configs
  - WindowsBitmapWGLDrawable: Clip chosenCaps to RGBA888[0|8]
  - WindowsBitmapWGLDrawable: Only use BITMAPINFOHEADER.BiBitCount=24
  - WindowsWGLGraphicsConfiguration: Only allow GDI BITMAP PFD's w/ RGB888 w/ alpha <= red, others may fail

- WindowsWGLGraphicsConfigurationFactory.getAvailableGLCapabilities()
  - Fetch ARB caps w/o BITMAP
  - Concat GDI [BITMAP] caps
GLJPanel.toString(): Avoid NPE
Fix Bug 720: Unify all platform specific GLContextImpl specializations; Fix Bug 719 - Windows BITMAP Offscreen Orientation is not propagated through API

Fix Bug 719 - Windows BITMAP Offscreen Orientation is not propagated through API
  Depends on Bug 720, since cleaning up GLContextImpl* is required to move
  property 'GLContext.isGLOrientationFlippedVertical()'
  to 'GLDrawable.isGLOriented()' where it belongs!

  Windows BITMAP GLDrawable impl. isGLOriented() shall return false,
  while we keep the BITMAPINFOHEADER's height field negative
  to remove the need for vertical flip when used w/ AWT or Windows, ..

  Then property 'GLDrawable.isGLOriented()' has to be recognized throughout the
  utility functions, i.e. TextureData's mustFlipVertically and hence TextureIO writer.

Fix Bug 720: Unify all platform specific GLContextImpl specializations
  GLContextImpl shall have only _one_ unique platform derivative
  to allow proper swapping of GLDrawables of any type via:
    - 'GLAutoDrawable.setContext(GLContext newCtx, boolean destroyPrevCtx)', which calls
    - 'GLContext.setGLDrawable(GLDrawable readWrite, boolean setWriteOnly)'

  Exception: External context may be specialized.

  All drawable specific property handling shall be provided
  and implemented (if possible) via GLDrawable specializations.

- GLContext.isGLOrientationFlippedVertical() -> GLDrawable.isGLOriented()
  - PNGImage.createFromData() takes 'isGLOriented' to properly handle vertical flipping simply by line ordering
  - TextureIO's PNG writer passes TextureData's getMustFlipVertically() as isGLOriented to PNGImage.createFromData()
  - GLReadBufferUtil respects GLDrawable's isGLOriented() when creating TextureData instance.
  - Screenshot respects GLDrawable's isGLOriented()

- Screenshot is deprecated, use GLReadBufferUtil.

- Removed all PBuffer attributes, i.e. floatingPoint, RenderToTexture and RenderToTextureRectangle.
   - Allows removal of special pbuffer handling in GLContext* implementations.
   - Removed also from GLCapabilities*
   - Removed from deprecated GLPbuffer

  Impact:
    - Low, users who desire to render into a texture shall use our FBO GLOffscreenDrawable.
    - Only use case was the deprecated GLPbuffer
    - floating point framebuffer technology is still patented anyways :)

- Removed Java2DGLContext, which was only used for OSX's GLJPanel Java2D bridge,
  which is no more supported anyways.
GLJPanel: setFocusable(true) at ctor to allow keyboard input