Geometry cleaning, continued

- [ ] Move the other geometries to a separate `filedata` repository (@filiatra , what do you think?) . For example, move the big geometries in [filedata/surfaces/neon](https://github.com/gismo/gsUnstructuredSplines/tree/dc167fe3995d8fc1926abe8b8d6eca505f1dbf8c/filedata/surfaces/neon)