Use Python 3 everywhere

Since Python 2 is retired in 4 months, we should move everything to 3.

CMakeLists.txt

@@ -265,7 +265,7 @@ endif()
 
 # python
 include(px4_find_python_module)
-find_package(PythonInterp REQUIRED)
+find_package(PythonInterp 3 REQUIRED)
 
 option(PYTHON_COVERAGE "Python code coverage" OFF)
 if(PYTHON_COVERAGE)

cmake/px4_find_python_module.cmake

@@ -65,12 +65,12 @@ function(px4_find_python_module module)
 		endif()
 	endif()
 	find_package_handle_standard_args(PY_${module}
-		"couldn't find python module ${module}:
+		"couldn't find python3 module ${module}:
 		\nfor debian systems try: \
-		\n\tsudo apt-get install python-${module} \
+		\n\tsudo apt-get install python3-${module} \
 		\nor for all other OSs/debian: \
-		\n\tsudo -H pip install ${module}\n" PY_${module_upper})
+		\n\tsudo -H pip3 install ${module}\n" PY_${module_upper})
 	#if (NOT PY_${module}_FOUND)
-		#message(FATAL_ERROR "python module not found, exiting")
+		#message(FATAL_ERROR "python3 module not found, exiting")
 	#endif()
 endfunction(px4_find_python_module)

msg/tools/px_generate_uorb_topic_files.py

@@ -55,11 +55,11 @@ Required python packages not installed.
 
 On a Debian/Ubuntu system please run:
 
-  sudo apt-get install python-empy
-  sudo pip install catkin_pkg
+  sudo apt-get install python3-empy
+  sudo pip3 install catkin_pkg
 
 On MacOS please run:
-  sudo pip install empy catkin_pkg
+  sudo pip3 install empy catkin_pkg
 
 On Windows please run:
   easy_install empy catkin_pkg

src/lib/mixer/MultirotorMixer/geometries/tools/px_generate_mixers.py

@@ -44,10 +44,10 @@ try:
 except ImportError as e:
     print("python import error: ", e)
     print('''
-Required python packages not installed.
+Required python3 packages not installed.
 
 On a GNU/Linux or MacOS system please run:
-  sudo pip install numpy toml
+  sudo pip3 install numpy toml
 
 On Windows please run:
   easy_install numpy toml