FPV Freerider demo

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- fixed some controller calibration stuff
Other recent changes include:
- revised quadcopter sound
- slightly revised crash system
In the full paid version there is also these additions:
- new flight mode: 3D (enables negative thrust/inverted flying)
- two save slots for custom user settings
- motion blur option in custom settings
- the Playground scene has been edited (removed some planks and logs to open up for more proximity flying opportunities)