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.

ReadOpenGLExtensions() calls this->RenderWindow->Render() on Win32 machines if Render() has not previously been called. This caused a crash, because Render() calls vtkOpenGLRenderWindow::OpenGLInit(), which was in turn calling vtkOpenGLRenderWindow::SetExtensionManager(0) and then creating a new ExtensionsManager.  The crash only seemed to occur on VS2003. See bug report for more details.

This fixes the issue with TestGlyph3DMapperPicking test.

* Cleaned up code between vtkPolyDataMapper and subclasses to avoid redundancy.
* Remove API from vtkCompositePainter to color leaves. That was added in
  anticipation for support for selection, but we have a different implementation
  for that now.
* Extended vtkHardwareSelector to add a pass to identify composite-ids for the
  points/cells.

Specifically, test vtkLogLookupTable and
vtkDiscretizableColorTranferFunction.

Check that there is an argument+1 before accessing it, otherwise any of
the command line switches taking a following argument could segfault if
that second argument was missing.

Tests that use vtkRegressionTestImage usually call the method with one
parameter. The second parametr is the error threshold and the default
in vtkRegressionTestImage.h is 10.

The vtkTestingInteractor now has an ErrorThreshold static
variable. vtkTestObjectFactory.cmake now parses the command line of a
test for -E error-threshold. This new flag can be placed on ADD_TEST
commands for tests that may have image error variation on different
platforms.

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

This reverts commit f1c243b6.
It wouldn't allow one to go back into the loop.

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