Added unit test and annotation for moment generation (3D Similarity)

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Added missing literature reference, and minimal additional information requested in bug #1285

Change-Id: Id4b46baf50130af657cf1c28cd7ce24b96a240aa
Signed-off-by: John May <john.wilkinsonmay@gmail.com>