Added 3 parallel classes and related tests.

Added vtkSMPWarVector, vtkSMPTransform and vtkSMPContourGrid and the
related tests. These use fine-grained parallelism to process their input
using multiple threads.

Change-Id: I00ffdea559f9b5a30f1b1141664766e843ef4dc5
Added support for parallel execution of filters over composite data.

Added a new executive that allows the execution of a filter in
parallel over the blocks of a composite dataset. This required
some minor refactoring of the composite pipeline. Also added a test.

Change-Id: I4a319aa32d793eed745db78ef4cd344a474430a7
Added support for updating progress in a thread-safe way.

UpdateProgress() was not thread-safe. Added a mechanism to handle
progress in a thread-safe way. This required the ability to
completely change the way algorithms handle progress, which I
chose to do outside the algorithm class to minimize unnecessary
complication of a base class.

Change-Id: I640cdddbcf79039d7cfcc6e716b4a0d55d028c6f
Merge topic 'smp-filters' into master

a6509136 Added 3 parallel classes and related tests.
Merge topic 'smp-parallel-composite-2' into master

47306747 Added support for updating progress in a thread-safe way.
feee6d8a Added support for parallel execution of filters over composite data.