Includes:
- scan python scripts
- run python scripts from ns3
- replace visualizer file copy with configure_file to prevent cmake refreshes
- replace ns__init__.py file copy with configure_file to prevent cmake refreshes
- fix bindings scanning with cmake
- pass include directories to modulegen for castxml consumption
- add missing parameters of Recv in python-unit-tests.py
- change apiscan targets from apiscan-module to libmodule-apiscan
- change bindings targets from module-bingings to libmodule-bindings
- scanning and bindings build tests
- scan scratch python scripts
- replace FindPython3 with FindPython to be compatible with CMake 3.10
- do not export private visual-simulator-impl.h
- do not export udp-socket-impl.h
- use .so suffix for bindings on Mac instead of .dylib
