- Add (many) functions needed to draw THStack

- Use 'this' in obj functions instead of 'obj' (to make sure the proper instance of the object is used/modified)
- Use jQuery to properly copy (clone) objects. With the previous method, modifying a cloned object was modifying the original object as well
- Use simple "if ('member' in obj)" test format instead of "if (obj['member'] && typeof(obj['member'] != 'undefined')"


git-svn-id: http://root.cern.ch/svn/root/trunk@47995 27541ba8-7e3a-0410-8455-c3a389f83636