Exclude text rendering classes from Tcl smoke tests.

The MatplotlibMathText utilities New() method performs a runtime
check for a valid python environment that has matplotlib installed.
If not found, the New() method returns NULL, which is causing a segfault
on these classes, since the class is not meant to be used directly, but
through the vtkTextRenderer layer.

Change-Id: Ie6a831b1a245969033538f9f3b8013702baeaecc
Merge topic 'fix-tcl-matplotlib-failures' into master

8a40614e Exclude text rendering classes from Tcl smoke tests.
Correct incorrectly calculating min and max cell for each piece.

Previously we incorrectly calculated the min and max cell
for each piece if we had less cells that pieces. This was
caused by using integer division instead of float division.

Also I correct the issue that if we have zero cells we would
divide by zero causing VTK to crash.

Change-Id: Id7f99dfa0b6b85727f326a38c62ada16af8a51ac
Merge topic 'update_extract_ugrid_piece' into master

8a73bfeb Correct incorrectly calculating min and max cell for each piece.