Modifications:
1. Adding a task is now more streamlined. Adding a task uses the
standard EditorActivity dialog that then allows picking a location from
the map by SHORT-clicking on the map.
2. Adding a task from the map (functionality added by Marc) has been
preserved, except that it now requires a LONG-click on the map (so as not
to interfere with short-click behavior in bullet 1 above).
These changes mean that we can now change the location of an existing task.