COMP: Add option allowing to enable internationalization support.

STATUS
 Internationalization support has been discussed during March 26th 2013
developer hangout.

 We reach consensus: Official support for i18n will be disabled. A CMake
option named Slicer_BUILD_I18N_SUPPORT will be added and the option
won't be actively supported or tested.

 Why? Supporting internationalization properly would require to test
all ITK/VTK/Teem/.. readers and we don't have the funding or resources
to support that effort. If it is something you are interested in, make
sure to drop an email on the developer list. We will be happy to provide
 more information.

DISCUSSION
 http://slicer-devel.65872.n3.nabble.com/Re-Rounding-to-integer-tt4027985.html
 http://slicer-devel.65872.n3.nabble.com/Re-slicer-users-Slicer4-can-t-really-use-it-yet-td4028040.html
 http://slicer-users.65878.n3.nabble.com/Slicer4-DICOM-many-problems-td4025919.html

ISSUES
 3029 - Image spacing not read correctly in Slicer 4.2.2

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21856 3bd1e089-480b-0410-8dfb-8563597acbee
ENH: 1318. Added FOV based on Volumes, resolution based on 2D View mode into reslice functionality

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21857 3bd1e089-480b-0410-8dfb-8563597acbee
BUG: Make sure the node is present before saving in a collection

While updating the scene, the tree view hierarchy was being saved. This causes
segfaults when updateScene is called after closing the scene or deleting nodes.
Check if the nodes are still present before saving them to collection.
Fixes issue 2557.
BUG: Save tree before the batch processing starts and restore after it ends

Saving the tree expansion state now happens before batch processing starts and
the consequent restoration happens after batch processing ends. This prevents
handling tree when the scene is in an inconsistent state during the batch
processing task.