Faster, more reliable (?) scene transitions

Today's challenge has been tracking down the cause of the reports I'm getting that sometimes the game gets stuck when transitioning between spaces.

The tricky part is that it never happens to me!

So today I rewrote a good deal of the code that handles transitioning between scenes. If it's not more reliable, it is at least more careful and will hopefully leave much better clues as to the source of the problem.

A nice side bonus is that it's much faster to wander through the chain forest now.

Thanks for playing and for the patience of those affected by the transitioning bug.

Cheers, Ziba