Camera controls in nin

Adds a cameracontroller to dasBoot.

Also a GUI in nin for extracting current camera position and lookAt
(more to come).

In addition, you can activate Fly Controls to look around for
interesting camera spots.

Camera paths are defined in `{PROJECT ROOT}/res/camerapaths.json`.

Any 3D layer that wants to use the camera controller can obtain a
reference to a controller by passing its layer.position to the
constructor (this forces camerapaths.json to have an entry for each
layer, though...)

More information in readme