Fixes #1861  "Prime" the gravity tracker so that the standard menu
item order is always obeyed.

Change-Id: I96d135ad68bf62bf300191b85335536f5820f386
Added some tests to make sure simple meta-edges are working right.

Change-Id: If7c390aef4796dbd7584357f605c267e4abde821
Fix significant problems with groups that were discovered when I fixed
some 2.8 metanodeplugin issues

Change-Id: I2b6ea8ad0690cacb724cf3d774043329f8d2ec03