Test scene re-organization, updating references to UnitySteer 2.6dev

We no longer need TickedPriorityQueue independent from UnitySteer,
since it'll be included with the code.

Imported project on Unity 4.
Removed unused classes
Forcing asset serialization to text
Merging development into master before repo clean-up
Cleaning up repository before starting to work on new examples

The new UnitySteer examples will be done completely from scratch, so
I'm cleaning up the old repository meanwhile.
Added README, License