AP_Param: removed copy_name() and add token to find_by_index()

this allows callers to avoid another var_info traverse
Rover: update for new AP_Param API
Plane: update for new AP_Param API
Copter: update for new AP_Param API
MAVLink: cope with available() returning -1
autotest: use mktemp instead of tempfile

more portable
autotest: fixed jsbsim on fedora
autotest: ensure JSBSim is dead on restart