hit() now must respect touchable and visible. Touchable only applies to the actor...

hit() now must respect touchable and visible. Touchable only applies to the actor itself, child actors can still be hit. This allows actors (like Table) to be invisible to touch events.
Table has touchable false by default.
cancelTouchFocus is a monster. :( Has to be this way to be reentrant and not cause problems when used from other events. There are probably still some problematic scenarios, but this hopefully covers the common ones.