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
BUG: Remove multiple per-pixel allocations in Mahalanobis Membership

When using the VectorConfidenceConnected filter multiple per-pixel
dynamic memory allocations were being performed. This patch removes
that by manually doing the vector matrix vector operation, with out
creating any temporaries. It was observed that this gave a 1.8x speed
up when segmenting the blue ice in the Visible Human.

Change-Id: I54c4a40604bd10d32ec4c401c3f195d436028045
Merge topic 'regExplsChangeTov4_r5'

cc0b553a ENH: Convert seven ImageRegistration examples to ITKv4
765a55c9 ENH: Prepare for ITKv4 registration Examples
Merge topic 'RemoveMemoryAllocationMahalanobisDistMem'

c5346503 BUG: Remove multiple per-pixel allocations in Mahalanobis Membership