Construct a fuseView only if needed
Fix crash cases
Reset Undo redo stack after closing either the fixed or moving view.  fixes #1769
Remove a useless if condition and comment
Keep window level, avoid crash when removin fixed view after run an algo.
No more crash but window level not alwayssync between fuse and compare views.
Keep sync between fused and compare view even after removing one. Thx gpasquie.
Bug corrected: when removing a layer in the fuse view, the corresponding
view in the compare tab was not closed
Merge pull request #110 from rdebroiz/1769-Registration_crash

1769 registration crashes
First steps towards rbZoom
-Solves the lost of control of focus over containers
-Improves rbzoom activation
-keyevent from qvtkwidget are sent to medMainWindow enabling the
activation of shortcut via keypressevent and keypressrelease
Small changes
-Now after choosing zoom as the main mouse interaction the focus is
directly brought back to the view.
- A new shortcut has been defined for the histogram
- This commit desactivates most of the key shortcuts that were existing in
  the code of vtkInria.
Removes useless lines
Resolves the rbzoom bug appearing when the ctrl key is pressed when the application loses focus
I added a new class vtkInriaInteractorStyleRubberBandZoom which inherits
from vtkInteractorStyleRubberBandZoom, this class will enable us to
reimplement some function to our advantages. Now the ctrl + right click
activates the rubber band zoom in all modes.
Gets rid of a lot of warning messages - Removes all the commented lines
activating useless shortcuts - Reactivates the 'r' and 'n' shortcuts.
This commit:
- changes the shortcut for histogram feature to ctrl + H
- removes the shortcut for the angle widget
- synchronize the zoom between view when the reset shortcut is used or the
  rubberBand Zoom
Hack to not have eventFilters everywhere
Fixed Ctrl+Space