ENH: Adding method to set global physical space tolerance

Adding global variables and accessors to the ImageToImageFilter to
allow setting the initial value for tolerances used to verify that the
physical location of image corresponds.

Change-Id: I69e8af8cfe1fb43e5e2807bc34451907bc9fe3f7
DOC: Index Wiki examples with Doxygen.

The wiki examples are indexed by doxygen so they will automatically be listed
with the class documentation and show up on the "Examples" tab page of
Doxygen.

ITK-3309.

Change-Id: I44245e1189c6d1fe7b585ba153c9d7f78efe58f5
COMP: Bump SphinxExamples remote module.

Fixes a CMake configuration error.

Change-Id: Ic1b09811748fa670e559e4f1b1c137d472f3b4f3
DOC: Index Sphinx examples in Doxygen.

The Sphinx examples are indexed by doxygen in the "Examples" tab and
are automatically cross-indexed in all the classes that they use.

ITK-3309.

Change-Id: Ic285cea7e65c348e9a978205c11d9684015acfc6
Merge topic 'doxygen-examples'

ade05411 DOC: Index Sphinx examples in Doxygen.
54299208 COMP: Bump SphinxExamples remote module.
0dc92b48 DOC: Index Wiki examples with Doxygen.
COMP: Add a check for Blocks in GPU module

See bug: ITK-3331

When compiling with ITK_USE_GPU=ON and macports gcc 4.9.2,
the compilation fails with errors like these:
/usr/include/dispatch/object.h:143:15: error: expected unqualified-id before '^' token
 typedef void (^dispatch_block_t)(void);

This patch checks for a working Blocks extension implentation.

More comments and explanations can be found in the itkCheckHasBlocks.cxx file.

Change-Id: I22a8d0fae62fbf33713f53879f0cda08fabb3d90
Merge topic 'AddGlobalDefaultTolerance'

9087aa4c ENH: Adding method to set global physical space tolerance
Merge topic 'GPUCheckBlocks'

d2c5c8a6 COMP: Add a check for Blocks in GPU module