ENH: Use pygccxml snapshot.

The pygccxml code has been moved from mercurial to git, and
is now hosted here: https://github.com/gccxml/pygccxml
ITK is still using version 1.0.0 until we have a stable
pygccxml version working with Python 2 and 3.

Changes:

1) Remove pygccxml folder from Wrapping/Generators/SwigInterface/
2) Pass the paths to pygccxml Snapshot and gccxml to the idx and igenerator module
3) pygccxml.parser.config.config_t() is deprecated and is now replaced by
pygccxml.parser.config.gccxml_configuration_t()
4) Removed some commented out and unused code, and moved the find_package(PythonInterp REQUIRED)
to the top of the SwigInterface CMakeLists.txt
5) Rename CABLE_INDEX variable to IDX_GENERATOR

Change-Id: I489675b506190ecc8f99f8258c33b09e03697a71
COMP: Fix Doxygen warnings in itkMetaDataObject.h.

Fixes:

  ITK/Modules/Core/Common/include/itkMetaDataObject.h:218: warning:
  documentation for unknown define NATIVE_TYPE_METADATAPRINT found.

  ITK/Modules/Core/Common/include/itkMetaDataObject.h:113: warning: argument
  'NewValue' of command @param is not found in the argument list of
  itk::MetaDataObject< MetaDataObjectType >::SetMetaDataObjectValue(const
  MetaDataObjectType &newValue)

Change-Id: I03a71ecbd20bbcb0bc09e8103bcfd84833a35adc
Merge topic 'UsepygccxmlSnapshot'

deccbdc1 ENH: Use pygccxml snapshot.
Merge topic 'doxygen'

45627e1c COMP: Fix Doxygen warnings in itkMetaDataObject.h.
ENH: Add an exception safe state restore class for streams

Programs that modify an input or output stream's format state should
restore that state upon return or before throwing an
exception. Otherwise the state remains in effect in subsequent uses of
the stream. For example, if a program modifies the precision of
std::cout using std::cout.precision(20), then the precision should be
restored to the default state upon return.

This class follows the RAII (Resource Acquisiton Is Initialization)
idiom to restore the state of a stream upon destruction of the class.

A few tests have been modified to use this class. Hopefully this class
and these changes will statisfy the Coverity defect: Not restoring
ostream format.

Change-Id: I5ddbc2207268d45fe2a7550a5e50f4646365ddad
Merge topic 'IosStateSave'

5b5e4b2e ENH: Add an exception safe state restore class for streams