Disable "BestAlternate" if no landable waypoint exist,
  avoid "WARNING : NO LANDINGS" message each 60sec...
Revert commit "fixed: not center Task point on task point move on slow devices".
This is intriducing a new bug, in pan mode the nearest searches is now related to task point and not to our position.
This is not the place to fix the slow devices problem. Instead, the cause of why a latency on slow devices is making the task point move not working  has to be searched.

	modified:   Draw/MapWindow_Events.cpp