Interface to elastix

Still necessary to add interfaces to transformix and the parameters
file.
Fixed order in test docstring
Fetch upstream and Merge branch 'master' into enh/ElastixInterface

Conflicts:
	CHANGES
New interface ApplyWarp using transformix
Some advances to implement all the interfaces
Added tests for new interfaces
Fixing test to pass
Fixed doctest example
Added PointsWarp interface to transformix
Fixed doctest example in PointsWarp
Fixing filename in doctest
Still correcting test
no comment
Added elastix to interfaces/setup.py
Added EditTransform interface

Now, basic operations (change reference image, and setting interpolator,
output pixel type, and/or output image format) are available.
Direction of displacement field should not be changed when changing target image in transformix
Merge remote-tracking branch 'origin/pr/849'

Conflicts:
	CHANGES