OpenGL error hunt

This patch implements OpenGL error checking in VTK.

OpenGL's error handling implementation error is designed such
that internal error flags remain set with the first error that
occurred until they are explicitly checked. With this design
it's important to check and clear the error flags regularly
else they become unusable as code checking for errors ends
up reporting earlier undetected unrelated errors.

This patch takes the following approach:

1) at public entry points into code that uses OpenGL clear the
error flags without reporting errors. This guards against
reportinig unrealted errors, such as those caused by code
outside of VTK. See vtkOpenGLClearErrorMacro

2) before returning from functions that made OpenGL calls check
for and report OpenGL errors. This detects Open GL errors in the
function/method where they occurred facilitating debugging and it
clears error flags so that user code doesn't detect errors caused
by VTK. See vtkOpenGLCheckErrorMacro

This patch cleans up a number of bugs that were detected by
the new error checking and reporting.

This patch also contains improvements for OpenGL pixel buffers, a
renderbuffer object, and fast paths through framebuffer objects,
and texture objects, and fast path for setting uniform variables,
all of which are needed in vtkSurfaceLICPainter and
vtkLineIntegralConvolution2D GPGPU code.

Change-Id: I4ecefe9a444a74128bf73ef2ddfd5d4acea387ec
Merge topic 'opengl-error-hunt' into master

a6fa3e37 OpenGL error hunt
OpenGL error hunt -- dashboard cleanup

use static version of the error macro
in QVTKGraphicsItem.cxx.

Change-Id: Iae2cf8d245d648d6f5120910c96224375a477f41
Merge topic 'opengl-error-hunt' into master

62311d5e OpenGL error hunt -- dashboard cleanup