* Fix TerrainPicking by not adding "ghost" collisions to the CollisionResults (which weren't removed).
Improve TerrainPicking by allowing to do more ray tracing (previously, it stopped on the first hit, now it will stop on the first hit within range).
* Upgraded TerrainTestCollision to support multiple collisions and print the collision results detailed. MultiCollision can easily be turned on/off in simpleInitApp().
During testing, I noticed a bug where in very rare cases the first collision isn't what is expected but the back side of the clicked mountain. It has to be validated if this is due to the following changes or was already present.
* Added Basic Unit Tests for Collision
* TerrainPicker: Change API to return int to conform with collideWith
* TerrainQuad: Conform with Picker now returning the number of collisions and allow to set multipleCollisions true or false.
* TerrainPicking: Fixed a bug where the perpendicular collision always returned true, no matter the result of checkTriangles.
Also add support for multiple collisions (which is toggleable to the old behavior, because the picker can early out then).
* Try to fix Travis Build
* Fixed a Regression which occurred due to Multi Collision Handling:
The method used to provide duplicate results, which is why I commented it out. This lead to corner-cases not colliding at all anymore, thus I added a unit-test and removed the commented code and instead made addCollision de-duplicate entries.
deep and semi-shallow cloning. I'd be very surprised if nothing
is broken as there is only so much testing I can easily do.
Also various fixes for places I forgot to call super.cloneFields().
