* Converted ETPropertyDescription and related classes to ObjC properties

* Fixed various missing setters that must be implemented to call -checkIsNotFrozen

* Fixed some small memory leaks


git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/EtoileFoundation@10292 7b3f36aa-e6db-49c1-8b4c-66eac1997e64