ENH: Prepare for ITKv4 registration Examples

The ITKv3 registration framework examples are moved
to a separate directory because they are needed
to ensure that a high degree of code coverage is
maintained.

Change-Id: Idb794a5c7a6fa61c98e58b4a413ab3703d70765d
ENH: Convert seven ImageRegistration examples to ITKv4

Seven registration examples are refactored to use ITKv4 registration
framework. Also, the explanations related to the deprecated
features are remove, and new explanations are added to reflect the
new features.
New examples related to the ITKv4 registration are set in a different
directory than ITKv3, and any conflict is avoided since the binaries
of ITKv3 examples are created using an "ITKv3" prefix to avoid any conflict.

Change-Id: I9b9f0d5e65eedfd38b92ba4504f45238d7c95ad5
Merge topic 'regExplsChangeTov4_r5'

cc0b553a ENH: Convert seven ImageRegistration examples to ITKv4
765a55c9 ENH: Prepare for ITKv4 registration Examples