ENH: Perform download of ITK tag file during build time

Use a cmake custom command to run a CMake script during build time to
download and unzip the download.

Change-Id: I31e4b122868bae736b3b425296712a4cecde035d
Patch to remote -k flag for gzip
Updating ITK tag along 4.6.0 release

Change-Id: I9a8591db4e61a79246be742704344736c97c63ce
Hide visibility warnings

Suppress warning from RHEL5 GCC 4.1 about visibility change.

Change-Id: I41ac9546339f5ca77747c141547122dce1c8b747
Merge topic 'DoxygenWithITKTagsDuringBuild'

ef3b3f09 Patch to remote -k flag for gzip
22b9f5b4 ENH: Perform download of ITK tag file during build time
Merge topic 'SIMPLEITK-543_UpgradeITKTowards4.6'

704c92c3 Updating ITK tag along 4.6.0 release
Merge branch 'FixVisibilityWarning' into release

* FixVisibilityWarning:
  Hide visibility warnings

Change-Id: I0966a9f98b3db9c9452a6c86421497ce75078b59
Merge branch 'release'

Change-Id: I7629ad6cc09929a3d93e2ec07e6074c723494520