694 avoid player leaving the scene through wallsfloor

This release incorporates the changes by @SarahAugustinowski from pull request #713.
Builds for Windows and Linux are available below.

Details

This should fix #694 but only for DesktopPlayers. VR-Player Movements are not fixed yet.

A charactercontroller and its method Move is now used to move the Player instead of using transform.position.
Every object which has the default-layer is ignored by the collider-check of the charactercontroller, so i introduce a new layer "BoxCollider".

There might were some problems with merging master into this branch. For this case, here is a overview about changes done in SEEWorld:

• added empty objects in "3D Models/Structure"
• added Boxcollider to each empty around the office sceen
• added a layer called BoxCollider to project and assign it to the before named empty objects

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See original pull request for details.