ENH: Update ITKv4 project to include latest release branch changes

This commit updates the version of ITK to what will be the 4.6.1 patch
release.
$ git shortlog 056d97b66..554e46a1
Christopher Mullins (1):
      COMP: Wrap MeshBase templates

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23727 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: Update ITKv4 to include fix for repeated call to "find_package(ITK ..)"

Associated gerrit topic is:

  http://review.source.kitware.com/#/c/16963/

// ----------
Author: Brad King <brad.king@kitware.com>
Date:   Wed Sep 10 09:22:34 2014 -0400

    BUG: Fix itk_module_config for repeated calls

    Fix use of _${ns}_${mod}_USED settings to block reporting a module more
    than once in a single itk_module_config call.  Do not leak the
    _${ns}_${mod}_USED settings outside a single call to itk_module_config
    so that a future call to the macro with the same ${ns} will use a fresh
    set of modules.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23728 3bd1e089-480b-0410-8dfb-8563597acbee