Misc. Cleanup and upgrades

- Removing unused panelmenu.js
- Adding alternative to the deprecated reparent method (see #1131).
 - usage: global.reparentActor(actor, parent);
 - parent can be null.
 - does not care if actor already is a child of parent, so it can be removed and appended to the end by doing global.reparentActor(actor, actor.get_parent()).
- Refactoring log initialization out of the start method.