Add block amount of detail information key

Change-Id: I485c0f934e9f69b4f8ecba782cd47eb914262627
Block opacity and color are now more independent

Block opacity can be set while still showing the colormap of the data.
Block color must now be set in order to override the mapper's color map.
Only works when Interpolate Scalars Before Mapping is on and
SetColorModeToMapScalars() has been called (if you want the backface
visible).

Change-Id: I159eeeb068f1ac1fbd49eded0d0f43d6b392508d
BUG: ImageAccumulate overflows for large images

If, in a large image, the count for a bin exceeds the max for an
integer, the count overflows and reports the wrong value. This patch
changes the output of ImageAccumulate to an image of vtkIdType.

The patch include a test. To truly validate a configuration, the dimensions
for the test should be set to 2048. For routine testing a small
dimension is recommended.

This bug was uncovered and analyzed by Gib Bogle while trying to use
ImageAccumulate on very large tiff images.

Change-Id: I284bf503e59461acf2c2d1ffb340daa4979582c2
Updated vtk point picker

Change-Id: I673f82569736d9249affa08ee6eb78465deb4b15
Added support for rendering when clipping by near plane

Change-Id: Ibe45190687c1dc4db5dad19b84c0baca8d09bbb6
Fixed volume geomety not updated

Change-Id: Iecbd96717063522378e40a605e65ab6c361d3a78
Using smallest possible delta to offset precision issues

Change-Id: I14cfd14ecb65786539e932dd281e9a2fa6c73a3b
Fixed release graphics resources

Change-Id: I7043207b1b260ad4b7865f6247045149ca2fa81a
ENH: Additional tests for new volume mapper

Change-Id: I545dba94bcfbaeea7bd855b3bad83f9b13bc9824
Remove unused variable.

Change-Id: I8185786ef250739449cde7a49985768d01574245
Merge topic 'uvcdat-sync' into master

25a270dd Remove unused variable.
949b8620 Updated vtk point picker
ENH: Added baselines based generated using old volume mapper

Disabled TestGPURayCastCropping1 to be fixed later.

Change-Id: I643d17283ca67104cc0abe52e5079dbb3508616d
Merge topic 'new_volumerenderingtests' into master

7e69bad4 ENH: Added baselines based generated using old volume mapper
52f78f2d ENH: Additional tests for new volume mapper
Merge topic 'volume_clipping_updated' into master

d2d49e01 Fixed release graphics resources
9dbe622e Using smallest possible delta to offset precision issues
4c9403a3 Fixed volume geomety not updated
14800322 Added support for rendering when clipping by near plane
Reduce code duplication for Start() method.

All the interactor subclasses had duplicated code in their Start()
methods, so I moved the common code into the superclass, and made a
new protected method called StartEventLoop() that contains all of
the OS-specific code.

Change-Id: Ib710fad013aa9400d21241cf285c23b4a6cdad9f
Ensure python header version matches lib version.

There was an error in the foreach() loop over _Python_VERSIONS.
Even if the python library for a specific version was not found,
it would try to find the include file for that python version.
As a result, it could very easily find the include file for one
version of python, and the library for another version.  This has
been seen to happen on OS X, but could happen on any OS.

Change-Id: I90157ba517dadd7d1ba0ce1f5dba523246064581
Remove the deprecated PYTHON_INCLUDE_PATH variable.

This variable has been deprecated for years and its presence can
lead to extreme frustration.  If it is set in the cache, then it
is used as the PYTHON_INCLUDE_DIR.  That means that if someone
removes PYTHON_INCLUDE_DIR from their cache (e.g. while trying to
debug their build), then cmake will set PYTHON_INCLUDE_DIR from
the internally cached PYTHON_INCLUDE_PATH instead of searching the
system for Python.h like it should.

Also fix the variable names in the documentation for this macro,
which were different from the names of the variables that were actually
used.

Change-Id: I55d54b9d05085118c97a2e1d417e8e6b31289f8a
Re-added gradient opacity

Change-Id: I3663c0aa6a63cb2848b218df8bf3689972c27c3f
Wrapped long lines

Change-Id: I4bc884eb7e7cf847bdba1539e59e76e5936b9a2e
Organzied the code bit better

Change-Id: Ic2583f8a9f1f96cd5f59fdb749dfa9aabd9c50a6