ENH: Add option to return an ordinal lookup table.

Whilst the original intent of this class was to create lookup tables
 of categorical data, it was not clearly documented. It is also useful
 to build lookup tables with ordinal data using these palettes.

Accordingly an option has been added to BuildLookupTable and
 CreateLookupTable to allow the user to optionally specify ordinal
 data.

The documentation has been improved to highlight the fact
 that a lookup table set for categorical data is returned by default.

A new test has been added, called TestColorSeriesLookupTables.cxx, and
 TestCategoricalColors.cxx has been fixed to actually test the colors,
 its previous behavior was to just print out the colors.

Change-Id: I90d9747477a4ea878e68a47e4d9519876e0c30ec
Signed-off-by: Andrew Maclean <andrew.amaclean@gmail.com>
Merge topic 'add_parameter_to_LUT_generation_in_vtkColorSeries' into master

2ad67533 ENH: Add option to return an ordinal lookup table.
python: install packages properly

With the trailing slash, CMake will merge the directories rather than
installing the directory as its own entity.

Change-Id: I7b39c0309f27e41476bea43ffd4a624e18b786ed
opengl2: use STATUS for the OSMesa message

Change-Id: I3c9a128fd92e31969f27e89fe9cdaf96d8652601
Merge topic 'opengl2-osmesa-message' into master

161541c8 opengl2: use STATUS for the OSMesa message
Merge topic 'fix-python-installs' into master

8e8f6477 python: install packages properly