Use PySDL2 instead of pygame for joystick support
Remove useless files as the corresponding feature has been dropped
Update the doc according to
Merge branch 'bluetooth-for-ps4-controller' of https://github.com/debona/crazyflie-clients-python into debona-bluetooth-for-ps4-controller

Conflicts:
	lib/cfclient/utils/joystick/linuxjsdev.py
	lib/cfclient/utils/pysdl2reader.py
Merge branch 'debona-bluetooth-for-ps4-controller'