vtkLineIntegralConvolution2D_fs1.glsl was using bReset in an expression to
compute tcord0. As it was not a conditional, there was a texture fetch on a
uninitialized texture. The result could be NaN or undefined and this value
multiplied by (1-bReset) would lead to a NaN or undefined result that would
propagate to the final value of tcord0 even if the actual value of (1-bReset)
is 0. The fix is to use a conditional statement instead.

Specifically, test vtkLogLookupTable and
vtkDiscretizableColorTranferFunction.

Non-finite scalars are NAN, INF, and -INF.

The baking is done in vtkShadowMapBakerPass, the use is done in
vtkShadowMapPass.

There is a Cxx version that works fairly reliably.

It randomly/inconsistently fails all of the place for no obvious
reason. There is a Cxx version of this test passes fairly consistently.

This included creating the appropriate OpenGL class, renaming the
classes from vtkKWE to VTK, and moving the appropriate Tests.

Made the global renderer in TestAreaSelections static.

STYLE: Added description.

returns TRUE.

LIC tests. Also added were the datasets and baseline images
used by the LICtests.

BUG: Add ResetCameraClippingRange to some tests that were failing under Mesa.  For some reason, having a texture (or image actor or volume) in the scene was causing the OpenGL DEPTH_TEST to be ignored, but resetting the clipping range before the render fixes this.

BUG: since the depth check seems to fail under Mesa for this example, force backface culling to get it to render properly

STYLE: Changed comments in vtkTriangle and vtkPolygon so that header files do not contain details about implementation.

ENH: Before capturing the window, do two renders and disable reading the front buffer. This strategy should prevent the capture of windows that are covered. It is the same stratgegy used by vtkTesting to capture regression test images.

IF(VTK_USE_DISPLAY)
to
IF(VTK_DATA_ROOT)

in
VTK/Rendering/Testing/Cxx/CMakeLists.txt
because they would fail if DATA_ROOT was not specified.

STYLE: added description for ComputeArea in vtkTriangle.h and vtkPolygon.h

ENH:Added vtkTDxInteractorStyle, vtkTDxInteractorStyleSettings, vtkTDxInteractorStyleCamera. Simplified TestTDx accordingly. Now, vtkInteractorStyle delegates TDxEvents to a vtkTDxInteractorStyle.