MetaIO (reduced)

This corresponds to commit hash
  53aa417f83a4c3606b06b673617a1f7b2f3a9f87
from upstream repository
  git@github.com:Kitware/MetaIO.git
ENH: Adding License file from upstream MetaIO
ENH: Adding script to update MetaIO from upstream

Change-Id: I4e51312785cc417eb3939941fbc583fe7e9ec516
ENH: Remove ITK MetaIO to prepare for upstream import

Change-Id: I7f9af5f30c6ed10fd07ff54aa220e3ce4305f40b
Merge branch 'MetaIO-upstream' into MetaIO-update

To initialize this subtree the following command was done:
git merge --no-commit -s ours MetaIO-upstream
git read-tree --prefix=Modules/ThirdParty/MetaIO/src/MetaIO/ -u
MetaIO-upstream

This patch address JIRA issue ITK-3232:
MetaIO reader crashes with empty string values

Change-Id: I27cda7d19bb87d97c28aae43b9c68628d3275033
Merge topic 'MetaIO-update'

13f4070d Merge branch 'MetaIO-upstream' into MetaIO-update
c00eb5b4 ENH: Remove ITK MetaIO to prepare for upstream import
0f479f88 ENH: Adding script to update MetaIO from upstream
ee293cc2 ENH: Adding License file from upstream MetaIO
23a51d63 MetaIO (reduced)
ENH: Add GetCurrentStepLength to RegularStepGradDescentOptv4

The ITKv3 version of RegularStepGradientDescent optimizer, it could return
its current gradient step length. Knowing current step length can be
useful in observers to track the optimization process.
One good application would be in multi-resolution registration, where we
can change the stop criteria of the optimizer at each level while we keep
the continuity of the steps between different levels.

Change-Id: I6b9dd181c9be25cace9f6eca697942fdf0c12432
ENH: Make ITKv4 compatible with ITKSoftwareGuide

ImageExamples 1 to 9 are reviewed in RegistrationITKv4 directory.
Those examples has been already converted to ITKv4. By this patch
I reviewed all the comments parts related to the ITKSoftwareGuide.
Please review my explanations about the ITKv4 registration framework.

Change-Id: Id3302e0cd54bd5f8abf89721d0eb804a999a55cd
WIP: initial conversion of multi1

Change-Id: I1301110a030e76b2c9d811de7303dbfc7c726b2d
WIP: multi res1

Change-Id: I879114a71dfba46b5f6f4906a1d1151220c69145
WIP: more changes to multiRes1

Change-Id: I25a04eaaa5a86f4c4772b8434512073708dc1cee
WIP: finish the multires1

Change-Id: Ib9ead20b7d375056b81aa34c4730b0d3a95c446f