Bug 776 GLContext Sharing: Add GLSharedContextSetter to SWT GLCanvas
GLDrawableHelper.reshape(): Catch pre-existing GL errors before glViewport(..) and dump it (Add stack trace if DEBUG)
Fix TestSharedContextNewtAWTBug523: Don't use VAO's w/ GL2 context - No VAO on GL2 ctx on OSX ; GLWindow #2 shall also use sharedDrawable; Cleanup  ..
Bug 876: BuildComposablePipeline: getGL*() shall not return downstream.getGL*() [TraceGL* / DebugGL*] ; Simplify GLContextImpl's set Debug/Trace Pipeline

Regression of commit 0002fccdcd6383874b2813dc6bbe3e33f5f00924:
  "Trace/Debug shall utilize downstream identification for isGL*() and getGL*() methods."

  Using the downstream identification commit is right for the isGL*() case,
  however, getGL*() returned the downstream object which makes the caller loosing the pipeline!

  Instead, we shall produce !GEN_GL_IDENTITY_BY_ASSIGNABLE_CLASS:

     "if( isGL<type>() ) { return this; }
     throw new GLException("Not a <type> implementation");"

  or for GEN_GL_IDENTITY_BY_ASSIGNABLE_CLASS:

     "return this;"
GLDrawableFactory: Add 'GLAutoDrawable createDummyAutoDrawable(..)' for convenience

Added:
  GLAutoDrawable createDummyAutoDrawable(AbstractGraphicsDevice deviceReq, boolean createNewDevice, GLProfile glp)
Bug 776 GLContext Sharing: Add copy-ctor to GLArrayData* w/ sliced Buffer; Refine GearsObject* GLArrayDataServer copying; GearsES*: Init VBO eagerly

Add copy-ctor to GLArrayData* w/ sliced Buffer to allow general sharing of VBO via these high-level types.

Refine GearsObject* GLArrayDataServer copying (commit bcfaa149b9803ce33c5a356cbcb45f7dfd3e4361):
  Utilize new GLArrayData* copy-ctor.

GearsES*: Init VBO eagerly, allowing VBO usage after init(..).
Bug 877 Concurrency Discussion: Update doc MultiThreading.txt, volatile field usage; GLDrawableImpl: Make read-only fields final.
Bug 776 GLContext Sharing: Fix copy-ctor GLArrayDataClient: Create new instance of GLArrayHandler of same type; Simplify GLArrayHandler inheritance.

Refines commit 9f2a9df0a4b7093925c8854b37fba053469a4b35
Bug 776 GLContext Sharing: GLSharedContextSetter API Doc: No 'Driver stability constraints' ; Fixing Test cases: Enable all, GearsObject*: Check VBO

- GLSharedContextSetter API Doc: No 'Driver stability constraints'
  - No driver issues ..
  - Use 'Lifecycle Considerations' to describe usage issues ..

- Fixing Test cases: Enable all, GearsObject*: Check VBO
  - GearsObject* needs to check whether VBO is 'still alive'
    if sharing is enabled.

  - Enable all unit tests.