Remove call to XGrabKeyboard from XOpenGLRenderWindow.

This call locks users into fullscreen paraview server windows,
disabling alt-tab, etc.

Change-Id: I71ea8bd354bf301d0462f4ce82683eaf3aca64d5
Algorithm doesn't apply ghost levels when not needed now.

Change-Id: I3e43d32e6e44b60702c8e3894c8080da4fbc3400
COMP: Adjust error threshold for TestDensifyPolyData

Some platforms report image errors with small differences. Here we
increase the error threshold for TestDensifyPolyData. Also, the
CMakeLists.txt file is instrumented to allow easy addition of new
error thresholds.

Converted TestDensifyPolyData to use the new testing framework. This
permits error tolerances to be specified in the CMakeLists.txt file
rather than hard coded in the test.

Change-Id: I7759465def406ccd0f761e3e478dd754806e084e
Merge topic 'NoXGrabKeyboard' into master

a5d9e847 Remove call to XGrabKeyboard from XOpenGLRenderWindow.
Merge topic 'TestDensifyPolyData_tolerance' into master

9abd425f COMP: Adjust error threshold for TestDensifyPolyData
Merge topic 'faster_extrac_piece' into master

9509182d Algorithm doesn't apply ghost levels when not needed now.