Rename registration SetTransform to SetInitialTransform

This renaming is more consistent with the ITK interface, the examples
and tests have been updated.

Additionally, the and "InPlace" flags has been added to the set method.

Change-Id: I7143d6801bde1ad2e7d6caf6ed88e4e5d7ed70dc
Adding testing for registration transform inplace option

Also accessor method to get the current state of the in-place option.

Change-Id: I549f7bd3ba8ea7abf120c685e6f08e0b9e455885
Merge topic 'SIMPLEITK-574_AddTransformInitialMethodsToRegistration' into next

c059562c Adding testing for registration transform inplace option
26d8ecb4 Rename registration SetTransform to SetInitialTransform
Adding documentation for SetInitialTransform method

Change-Id: Id905ba92d318d9531484513936cde009d48cf125
Merge topic 'SIMPLEITK-574_AddTransformInitialMethodsToRegistration' into next

fa1243c5 Adding documentation for SetInitialTransform method