add trajectory critic/generator

CMakeLists.txt

air_navigation_plugins.xml

include/air_navigation/py_interface.h

include/air_navigation/python_controller.h

include/air_navigation/python_interpreter.h

include/air_navigation/python_trajectory_critic.h

include/air_navigation/python_trajectory_generator.h

python/air_navigation/__init__.py

python/air_navigation/py_interface.sip

src/python_controller.cpp

src/python_interpreter.cpp

src/python_trajectory_critic.cpp

src/python_trajectory_generator.cpp