Add more models

- BR 01: https://sketchfab.com/3d-models/br-01-german-steam-locomotive-cdf7e415aa75441897c0b5dfb384302f
- BR 50: https://sketchfab.com/3d-models/steam-locomotive-drb-baureihe-50-39bf54a4d41b472688dde420c82960fe
- Wagon: https://sketchfab.com/3d-models/train-carriage-9937b74270244602b0e1e9744683644a