ENH: Add some more coverage for MultiThreshold

Add the convenience methods.
Skip code on win32 that involves NaN.

Change-Id: I4406ff0ca66842d1a32ddfcc2983810d3eedf3eb
Fix double to unsigned char cast error on clang compiler.

Change-Id: I3979f3eeb2407a9924e57cf4b8540ea67693807e
Merge topic 'FixBoxPlot_doublecast' into master

35261130 Fix double to unsigned char cast error on clang compiler.
Merge topic 'Improvements_UnitTestMultiThreshold' into master

6cb7f089 ENH: Add some more coverage for MultiThreshold
Merge topic 'update-vtk' into pv-master

7fe4ffb4 Merge topic 'empty-array-init' into master
4f1b4a13 Merge topic 'web-catalyst-composite-widget' into master
3bb60f29 better UI for catalyst re-sampler web widget
b6700dfb Better composite catalyst web widget
398af669 Merge topic 'vtk-surface-reconstruction-fix-origin-and-spacing' into master
90d75926 Handle empty array initialization in numpy_support.
618d6279 Merge topic 'vtkCellLocator-precision-issue' into master
9fc4c29d Merge topic 'Coverage_ParametricSpline' into master
5565b59b Merge topic 'phyloxml_tree_writer' into master
4b3de93f Merge remote-tracking branch 'pvvtk/pv-master' into HEAD
e2b5f16b ENH: Unit test for ParametricSpline
5a894ac2 Merge topic 'RemoveBogusLineInfo' into master
42415809 COMP: Remove bogus line info from generated files
c71d9c21 get the baseline file's path from the command line
81534288 add baseline directory
bba7656c improve the thoroughness of TestPhyloXMLTreeWriter
...
Merge remote-tracking branch 'pvvtk/pv-master' into HEAD

* pvvtk/pv-master:

Change-Id: I4b2d5f7089cb5e4d29453cfd97163a5aff0eb75a