Rename TODO to TODO.md and fix some markdown formatting problems

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10404 7b3f36aa-e6db-49c1-8b4c-66eac1997e64
COBranch: remove unused parameter in -init method (the passed COObjectGraphContext was nil in all calls to this method)

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10405 7b3f36aa-e6db-49c1-8b4c-66eac1997e64