Fix BuildComposablePipeline's isGL*/getGL* ; GLBase: getDownstreamGL()/getRootGL(); GLContext.isGL* added proper API doc., isGL3core()/hasNoDefaultVAO() and getDefaultVAO().

- Fix BuildComposablePipeline's isGL*/getGL* (regression of commit 3a0d7703da32e9a5ddf08a334f18588a78038d880)

- GLBase: getDownstreamGL()/getRootGL()
  Allows user traversing through pipelined GL instances.
  Also added getRootGL() to GLContext.

- GLContext.isGL* added proper API doc.: We test the actual context, not the profile.

- GLContext isGL3core()/hasNoDefaultVAO() and getDefaultVAO()
  - Move isGL3code() def. back to pre 3a0d7703da32e9a5ddf08a334f18588a78038d880, i.e. Includes [ GL4, GL3 ] w/o GLES3.
  - Added hasNoDefaultVAO() and getDefaultVAO() .. incl. [ GL4, GL3, GLES3 ]
Fix value range of CTX_* options bits, regression of commit 3a0d7703da32e9a5ddf08a334f18588a78038d88