AP_Math: bug fix to wrap_360 and wrap_180

angles above 720deg and below 3200deg might not have been properly
wrapped.
wrap_360_cd could return 36000 when really this should be wrapped back
to zero.
Copter: AttControl param prefix shortened to ATC
AP_Math: float versions of wrap_360 and wrap_180
AC_AttControl: add slew_yaw
AC_AttControl_Heli: adjust for new slew_yaw param
Copter: integrate slew_yaw into control_auto
Copter: compiler warning for control_autotune