Upgrade/paraview56 python37

This is a MR to upgrade paraview from 5.4 to 5.6.1 and python from 2.7 to 3.7 :

• We now use a forked version of paraview 5.6.1.
• The common-superbuild has been updated for a better management of python 2 or 3 (superbuild projects named python2 and python3).
• We have solved some issues in the case where concurrent python versions are installed in a machine. That is why we need exactly python version 3.7.
• We made some changes to take into account some API and class name changes.
• Now the python Shell and the message console are managed with some embedded Paraview classes and fully integrated in the UI.
• The VV prefix has been changed to LV in all cmake files.
• All the dependencies previously located in lib\lidarview-4.1 has been moved to lib. This avoid a duplication of some dependencies in lib and lib/lidarview-4.1.
• The bundle has been refactored to use new functions available from the common-superbuild and to take into account the new location of the dependencies.

So now apps and dependencies are organized as follow relatively to the CMAKE_INSTALL_DIR :

	UNIX	Windows	OSX
LidarView App	lib	bin	bin/VeloView.app/Contents/MacOS
SimLink Lidarview	bin	none	none
Other apps	bin	bin	bin/VeloView.app/Contents/bin
Calibration files	share	share	bin/VeloView.app/Contents/Resources
Dependencies	lib	bin	bin/VeloView.app/Contents/Libraries
Plugins	lib/plugins	bin/plugins	bin/VeloView.app/Contents/Plugins
Python modules	lib/python3.7/site-packages	bin/site-packages	bin/VeloView.app/Contents/Python
Python libs	lib/python3.7	bin	bin/VeloView.app/Contents/Python

TODO before merging :

• Wait for LVCore and Superbuild to be merged and updated
• Delete modification on CI
• Use public plugin submodule

@melanie.carriere PTAL