Factorize bundle files from Lidarview

See merge request !24

[fix] Instruct OSX to bundle LidarSLam.dylib

See merge request !22

The Bundle script needs ENABLE_slam variable to conditionally include LidarSlam.dylib

Enable python3 for the whole superbuild.

See merge request !23

This is needed for superbuild python project to use python3 interpreter.

Upgrade/paraview56 python37

See merge request !21

According to recommendations in SuperbuildMacros, patches should not be
applied to projects sourced from Git repository. That's why we get
sources from a PythonQt fork instead of using the superbuild_apply_patch
function.

In UNIX platform since python 3.7, _POSIX_THREADS need to be defined. If
it's not the case the native threads type is unknown and a build error
is returned from pythread.h.

On OSX, boost libs are missing when we try to launch lidarview app or tests.
Even if all the needed cmake flags are used for lidarview to managed
dependencies with RPATH, it remains an issue where RPATH are not used
to find boost libs. This script has been created to force lidarview to
search all boost dependencies along RPATH. (See related issue
here cmake/cmake#19315).

The module vtkmodules.vtkFiltersVerdict is needed to use VTK-NumPy
integration layer in python filter. As this layer is a useful feature to
link VTK data to NUMPY array, we turn vtkFiltersVerdict ON.
(See https://docs.paraview.org/en/latest/ReferenceManual/vtkNumPyIntegration.html)

This feature is used to enable Lidarview to use python filter.

We force python version to be exactly 3.7 as it is the only one tested.
USE_SYSTEM_python3 is used to define if python libs are directly linked
to the python3 system directory (USE_SYSTEM_python3=ON) or shipped
in the install dir (OFF) (See superbuild_python_install function).

FindPythonLibs or FindPython2 are used by several projects. Both set
some python variables than can enter in conflicts.
This fix ensure the superbuild projects to use the same python version.
It is only needed if a python system is required.

USE_SYSTEM_python is no longer used since the update of the
common-superbuild. Now USE_SYSTEM_python2 or USE_SYSTEM_python3 has to
be used.

This has been done to follow the steps to manage qt5 in the Paraview
Superbuild.

Since the common superbuild update qt 5.12 has become the default
version. With that version an error occurs during qt configuration step.
For now we use the version 5.10 already approved in LidarView.

Since the common-superbuild update, these superbuild projects
are missing. ffi is related to libffi and is a python3
dependency. utillinux is related to util-linux and is a fontconfig
dependency.

This is done to be consistent with the required version in
the common-superbuild.

The projects named python2 and python3 have been created to managed
the python major version we use. That is why we have added a python2
dependency to the lidarview project.

Restore Boost_LIBRARY_DIR* variables in PCL CMake configuration

See merge request !20

These variables should not be necessary, as BOOST_LIBRARYDIR is properly set.
It works as is on MacOS and Windows.
For some reason, on Linux, PCL still finds and uses the system Boost, ignoring these variables.
Boost_LIBRARY_DIR_DEBUG and Boost_LIBRARY_DIR_Release variables should be filled by CMake according to the BOOST_LIBRARYDIR hint.
By directly setting these variables, we ensure using the correct superbuild Boost libs.