So instead of updating plane.guided_WP_loc and then calling
set_guided_WP(void) to copy that state into plane.next_WP_loc we pass
the new location in the call to set_guided_WP(const Location &loc).
avoidance was the only place which was not entirely over-writing
plane.guided_WP_loc. However, plane.next_WP_loc was updated to be the
current location when we entered guided mode. If we update the
horizontal/vertical avoidance now it is relative to the current
location, not the guided wp location, which could be quite important.
Peter Barker
Iampete1