State machines

[nhaarman]

Using a state machine in a Navigator seemed one of the main advantages of using these Navigators when beginning to design the library. In practice actually, using state machines may prove to be more difficult than initially thought -- there's Scene management, View hierarchy saving, Scene state saving, etc. Combining these with a state machine is not that trivial at all.

Especially with the power that comes with the composing of Navigators, state machines become less necessary. There are definitely cases where state machines may be a better choice, but before that happens some more thought in how to actually implement Navigators with them is necessary.