G1000 knobs for PEC11D-4120-S0015

These models are derivatives from [this flight sim gadget, SimHID G1000](https://www.thingiverse.com/thing:4966493).
The original project applies ALPS EC11EBB24C03 as the dual shaft rotary encoder. However, this component is already in state of EOL.
Fortunately, [BOURNS PEC11D-4120F-S0015](https://www.bourns.com/products/encoders/contacting-encoders/product/PEC11D) is compatible with EC11EBB24C03 from PCB footprint and electronically characterisity, except for shaft geometry.

Therefore, I made another design of knobs for PEC11D-4120F-2015.