Fix for bug that throws array out of bounds error when editing the waypoints list

The IntermediatePointsDialog class throws an exception when the
waypoints list is edited (particularly if all points including the
Destination are selected for removal). The fix requires additional
methods in the TargetPointsHelper class in the OsmAnd-Jni project and a
fix and pull request have been provided to both projects
Merge pull request #413 from michc/fix_waypoint_editor_bug

Fix for bug that throws array out of bounds error when editing the waypo...