Planner: Control-Click removes divedatapoint and all following ones

In order to offer a simple way to remove a calculated deco, if Control is pressed
while clicking on the trash can in the dive plan, that point and all following are
removed. This way the user can Ctrl-click on the first calculated waypoint.

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>