BUG #15046, BUG #15020: Fix issues with OpenGL 1.2.

Believe it or not, we have use-cases where people use OpenGL 1.2! Soon
we won't support that. But until then, we should continue to support
it. Based on discusson on BUG #15020, making the missing FBO warning to
be shown only in debug builds. Also use GL_ARB_multitexture explicitly
when GL_VERSION_1_3 is not supported.

Change-Id: Id8ec2e902536fb3165e03bc05c6a9bd1fcbc03e8
fix a bug in value painting for cell arrays

I wasn't rendering the correct values because I didn't have the right
ids. With small data the cellarray and polydata indices happened to
be the same. In general they won't be.

Change-Id: Id1186c8fab3b0ba0ff2e640a6fd3d6075f690516
BUG #15058: Fixes unclipped grid.

vtkChartXY wouldn't clip the grid. There doesn't seem to be a good
reason for that. We should clip the grid to match
clipping/transformation used by the axes and other plots. This avoid
visualization where the grid extends beyond the axes/plots.

Change-Id: I5bd43f65f27f437832bf33ef6230084de7988367
Merge topic 'vtk_master_20141104' into pv-master

c3fcd2b3 Merge remote-tracking branch 'pvvtk/pv-master' into HEAD
736e15f2 Merge topic 'stencil-raster-tolerance' into master
51ebea64 Merge topic 'ImageCanvasSource2D-Improvements' into master
a42b7869 ENH: Added function to initialize volume
ab8ae4f1 Merge topic 'wrap_parallel_fix' into master
896b83f8 Fix RenderingParallel when wrapped and fix a compiler warning
69afec01 Merge topic 'fix_bad_merge' into master
e1d90d07 Fix a bad merge
ff981f6a Merge topic 'parallel_fixes' into master
a632e687 Merge topic 'OpenGL2-Texture-ClampBorder' into master
0b64c2e2 ENH: Added support for ClampToBorder (as it was in OpenGL)
3bba750a Merge topic 'silence-warning' into master
b9e849eb Merge topic 'opengles_fixes' into master
f497ed3a Added some ifdef needed for OpenGL ES 20
9b3d5ea3 Merge topic 'edge_vis_cpdm2' into master
893c3c5c Fix edge color with composite polydata mapper 2
...
Merge remote-tracking branch 'pvvtk/pv-master' into HEAD

* pvvtk/pv-master:

Change-Id: Ib51059d44d12c53af14d32825e1fb3fe18f92018
Merge topic '15020_fix_OpenGL-1.2_issues' into master

031f7f63 BUG #15046, BUG #15020: Fix issues with OpenGL 1.2.
Merge topic 'fix-cell-value-painter' into master

78108633 fix a bug in value painting for cell arrays
Merge topic '15058_fix_grid_clipping' into master

25e39389 BUG #15058: Fixes unclipped grid.
COMP: A more robust way to check file descriptor leaks

This patch counts the number of used file descriptors before and after
the I/O.

Change-Id: I94fbb66ce069f7f4f4d498a1ed54f9114eed2888
Merge topic 'AdjustFileDescriptorLimit' into master

ab29d100 COMP: A more robust way to check file descriptor leaks