Forward / Back History Stack Should Contain Entered World States

[robertlong]

When you browse between worlds and hit the browser back button it now adds an item to the history stack where you are not entered into the world.

For example I navigate to Room A then enter then Room B then enter. The history should only contain items for Room A and Room B. Currently there are items for Room A (Unentered), Room A (Entered), Room B (Unentered), Room B (Entered).