ENH: Implement feature 2885, display ruler projection on 2D viewers.

Add options to display the projection of a ruler on the 2D slices.

Code from Laurent Chauvin 
https://github.com/lchauvin/Slicer/commit/203b44301c0421d619d68e2ccd3a13dee0047cf0

Issue #2885


git-svn-id: http://svn.slicer.org/Slicer4/trunk@21649 3bd1e089-480b-0410-8dfb-8563597acbee
STYLE: remove debugging statement

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21650 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: fix typo in editor extension template

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21651 3bd1e089-480b-0410-8dfb-8563597acbee
COMP: Ensure itkFactoryRegistration code is included when building against ITKv4

See http://www.na-mic.org/Bug/view.php?id=2900

Fixes #2900

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21652 3bd1e089-480b-0410-8dfb-8563597acbee