Updated API to force use of vtkShaderCache

Change-Id: I5e4912282eb4a36a06b47bef48be709147f352fc
Updated volume rendering to use shader cache

Change-Id: I166929e05f50eea790888545678dc6019a59fc7f
Added error checks for volume render calls

Change-Id: I48e468b9bc08aa64fec115e35e2835233424218f
Using render window shader cache

Change-Id: If4f698114639fd796c917f5dabf4b2d96c126f7f
Fixed volume tests failing because of shader cache

Change-Id: Ic471c394e31925ae9fed012cc7bbeb90bb9ff769
ShaderCache should release its graphics resources

For the shader programs that it manages.

Change-Id: Ibddc8442cad1f1a652edc2277a37b5284f1283d2
Removed unnecessary call and added notes

Change-Id: I9b09ceba1ef624163d0199d59d05678e8b8f0e83
Let shader cache invoke release graphics resources on shader

Change-Id: Ic5820a41b4e75d66e5396054f20ab4f961107572
Attempt to fix failing test by removing calls to interactor

Change-Id: I6bd51fd735edeeea8ad5b16ea5125f588299de47
Added second baseline to fix failing test on some systems

Change-Id: Ib9426bef35449e089f4f8cee0d615a2867d33c17
Merge topic 'volume_geometry_fixes' into master

746fbdd7 Added second baseline to fix failing test on some systems
5948b78d Attempt to fix failing test by removing calls to interactor
4ef33909 Let shader cache invoke release graphics resources on shader
e3eb4735 Removed unnecessary call and added notes
652d7369 ShaderCache should release its graphics resources
454e0db7 Fixed volume tests failing because of shader cache
f1826bea Using render window shader cache
c5e5788d Added error checks for volume render calls
0c38ee5c Updated volume rendering to use shader cache
7bd46535 Updated API to force use of vtkShaderCache
14042: Numerical stability of vtkPolyDataToImageStencil.

When clipping the polydata to create the contours for the stencil,
use use a new "EdgeLocator" class that identifies new points by the
edge that was cut to make the point: each edge is uniquely identified
by the point ids of two ends of the edge.  This is more robust than
using a PointLocator, because the PointLocator is limited by machine
precision and can therefore cause errors in the connectivity of the
output of the cutting operation.

Also improve the code that handles loose ends and branch points (bad
contour topology) because its heuristics failed in common cases: now
loose ends are preferably joined along the hull of the contour, and
short branches (spurs) that go nowhere are removed.  Vertical
inflection points are no longer marked, because the code in
vtkImageStencilData to handle tolerances for inflection points fails
for horizontal line segments.

Change-Id: Ie9248de960250f94f3613bd34d8890e20ce39f26
Merge topic '14042_polydatatoimagestencil_robustness' into master

88ab5f7e 14042: Numerical stability of vtkPolyDataToImageStencil.