Merge branches 'deprecate-classes', 'zlib-soversion', 'unlink-agl',...

Merge branches 'deprecate-classes', 'zlib-soversion', 'unlink-agl', 'osmesa_32', 'matrix-cleanup2', 'solveleastsquares-memory-leak', 'python3_vtk_qt_fixes', '15914-reslice-mapper', 'release_splat_memory', 'km_coverity1', 'fix-cxx11-cmake-warning', 'fix-for-special-chars-in-dir' and 'ios-9.2-vtk7' into release

* deprecate-classes:
  Deprecating vtkVolumeRaycastMapper and vtkVolumeTextureMapper2D/3D.

* zlib-soversion:
  zlib 2015-12-14 (751703ae)
  zlib: remove zlib1.rc from the list of used files.
  zlib 2015-12-09 (acc12639)
  ThirdParty: Improve update script default merge message behavior
  ThirdParty: Teach update script to find upstream hash in commit message
  ThirdParty: Teach update script to store upstream hash in commit message
  metaio 2015-11-23 (4c85a18e)
  jsoncpp 2015-10-01 (eb1ddde0)
  png 2015-12-07 (63adbb10)
  zlib 2015-11-18 (0abb295c)

* unlink-agl:
  Remove AGL.framework from OS X OPENGL_LIBRARIES.

* osmesa_32:
  get a 3.2 context from OS mesa using new funcs

* matrix-cleanup2:
  Change deprecation warning to "VTK 7.0".
  Synchronize vtkMatrix3x3 with vtkMatrix4x4.
  Remove warning about deprecated method usage.
  Eliminate C-style casts from vtkMatrix4x4.
  Rename Element parameter to element.
  Mark legacy methods as "legacy".
  Remove the legacy BTX/ETX markers.
  Move some comments so they become visible to doxygen.

* solveleastsquares-memory-leak:
  Fix memory leak in vtkMath::SolveLeastSquares.

* python3_vtk_qt_fixes:
  Fixes QTVTKRenderWindowInteractor for python3

* 15914-reslice-mapper:
  BUG 15914: Fix corrupt image from vtkImageResliceMapper

* release_splat_memory:
  Free up memory in the point gaussian

* km_coverity1:
  Fix some coverity issues

* fix-cxx11-cmake-warning:
  fix a cmake warning for users of VTK

* fix-for-special-chars-in-dir:
  Fix CMake error if in directory with ++ in name.

* ios-9.2-vtk7:
  ios: fix newline-at-end-of-file
  update for newer versions of iOS