New backend() method in view API to access underlying implementation
adds a vtkImageView3d as a variable of the medVtkViewBackend, corrects an error in implementation

Conflicts:
	src-plugins/variationalSegmentation/varSegToolBox.cpp
Fix a crash on selecting the Jet LUT
Fix mesh exporters
Preliminary work towards a beautiful medInria (lol)
Add style sheet parser plus test
Set a new Style to medInria using qss
Add missing files
put a grey darker for the empty view container
Global reduction of the border-radius
improve aspect of the layout buutons
toolbox are darker
scroll bar are darker
harmonize pushButton and ComboBox with darker toolBox
correct padding for comboBox
stash
less contrast and slight modifications in qss
medQSSParser test doesn't link with libQtTest anymore (its a problem for osx).
darker button, combobox and medViewPropertyToolbox
darker checkboxes, radiobuttons and spinboxes when disabled and smaller font