Removed the "Show Cyclic Dependencies" operator for nodes. This operator is an old relic implemented for showing cyclic node connections as red links. This is not necessary any more, the operator simply
called the generic node tree update function, which is happening anyway after all relevant node operators (if it doesn't that has to be considered a bug).

It has been suggested to better use the C key for circle select, this remains to be discussed.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61172 954f8c5b-7b00-dc11-b283-0030488c597c