Cjio

Fixed
- crash with new version of Click (>=8.1) (140)
Added
- templates for bug reporting

Fixed
- STL export (127)

Fixed
- String representation of the CityJSON class works again

Fixed
- save operator was crashing for unknown reasons sometimes, this is fixed

Changed
- Minimum required CityJSON version is 1.1
- Many operators names changed, it's now "property-verb", so that all the operators related to textures for instance are together
- The metadata are only updated (with lineage) when there is a [metadata-extended](https://github.com/cityjson/metadata-extended) property in the file, otherwise nothing is modified
- The schema validator (operator `validate`) is not written in Python anymore and part of cjio, it's using [cjval](https://github.com/cityjson/cjval) and its [Python binding](https://github.com/cityjson/cjvalpy) (which needs to be installed). The validator is several orders of magniture faster too

Added
- A new operator `triangulate` that triangulates each surface of the input (de-triangulate coming soon)

Fixed
- Several bugs were fixed

API
- Loading a file with `cityjson.load()` removes the `transform` property from the file

Changed
- Minimum required Python is 3.6

Fixed
- Click option is set to None when empty (99)
- Loading breaks on inconsistent semantics (102)
- extract_lod doesn't work with the improved LoD (80)

API changes
- Added `CityJSON.load_from_j`
- Make transformation the default on loading a cityjson
- `CityJSON.add_to_j` includes `reference_geometry`, no need to call it separately