Add -parentNode to COTrackNode

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10463 7b3f36aa-e6db-49c1-8b4c-66eac1997e64
Typewriter: undo graph renderer: remove dependency on COCommandGroup

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10464 7b3f36aa-e6db-49c1-8b4c-66eac1997e64