FBObject: Fix depth- and stencil bit count selection for attachRenderbuffer(..);

- Fix depth- and stencil bit count selection for attachRenderbuffer(..)
  - Add generic values: DEFAULT_BITS, REQUESTED_BITS, CHOSEN_BITS, MAXIMUM_BITS

  - Refactor depth- and stencil bit-count -> format into own method

  - Allow depth- and stencil bit-count select a higher bit-count if required (fix)

- GLFBODrawable.FBOMODE_USE_DEPTH is deprecated, using GLCapabilities.[get|set]DepthBits(..)
  - It was an oversight to introduce the bit flag in the first place,
    since we should have used the capabilities depth bit-count

- Graph Test: GLEventListenerButton shall use requested capabilities for FBO drawable.
Add GLJPanelsAndGLCanvasDemoGL2Applet: Simple applet test for GLJPanel/GL2 testing (offscreen, ..); Clean up GL2 Gears and Teapot state enable/disable
TestVersionSemanticsNOUI: V221 -> V222 Add exception for GLFBODrawable.FBOMODE_DEFAULT