Fix Waypoint & Track visibility issues.

Fix Waypoint & Track visibility issues.

Problems:
1. If a waypoint is made invisibile, saved to a .vik and then the file reloaded the waypoint is visible.
2. If an invisible waypoint is cut/copied - upon paste it is marked as invisible.
3. If an invisible track is cut/copied - upon paste it has no visibility control.
4. If an track or waypoint is cut, a redraw event is done (as the item is no longer visible), however upon pasting it is not seen until a redraw event is triggered (eg zoom out).

Thus fixed add waypoint and track code to separate the control of the visibility checkbox and the setting of the checkbox itself. [Fixes 1,2&3]
Upon pastes, generate layer update if necessary. [Fixes 4]