Major changes in mikrokopter for lost connection
-In nav_lib.cpp, added main_loop, so we don't have to keep rewriting it
:). Also, this now publishes to /mk_wrapper/control, which should be
used from now on. However, old publish_on still works as it did.
-Changed turn_to_target and joystick_control (but not any others yet) to
use new nav_lib main_loop.
-Added mk_wrapper, which simply copies messages from /mk_wrapper/control
to /mikrokopter/req_set_control. After recieving the first message, if
it receives no message for a period of 200ms (rosparam max_quiet_time),
it will instead publish 0's and a thrust of 60, ignoring all future
input until restarted.
-Added launch files onboard.launch and joystick.launch, so that we
remember what should run where and can easily set some parameters.