Gdsfactory

- write and read Sparameters
- pp.extend_ports is now a container
- any component decorated with pp.cell can accept `pins=True` flag, and a function `pins_function`.
- Pins arguments will be ignored from the Component `name` and `settings`
- better json serializer for settings
- added units to names (m,K,G ...)

- leaf components (waveguide, bend, mmi ...) have now pins, for circuit simulation

- flake8 is passing now
- added flake8 to pre-commit hook
- simpler JSON file for mask metadata mask.tp.json
- added container decorator, can inherit ports, settings, test and data analysis protocols and still have a different name to avoid name collisions
- samples run as part of the test suite, moved samples into pp
- cell sorts kwarg keys by alphabetical order
- added cell tests
- cell accepts max_name_length and ignore_from_name kwargs
- pp.generate_does raises error if component does not exist in factory
- replaces name_W20_L30 by name_hash for cell names > 32
- zz_conn cleaner name using `from pp.cell import clean_name` no slashes in the name
- add_io is a container
- write labels settings in the middle of the component by default, you can always turn it off by adding `config.yml` in your project
- added pytest-regression for component setting and ports


with_settings_label: False

- mask JSON works with cached GDS files for the klayout placer
- added layers to CONFIG['layers']
- write_labels gets layer from `CONFIG['layers']['LABEL']`
- add_padding works over the same component --> this was not a good idea, reverted in 1.1.7 to avoid name collisions
- import_gds can snap points to a design grid

- added pre-commit hook for code consistency
- waveguide and bend allow a list of cladding layers
- all layers are defined as tuples using pp.LAYER.WG, pp.LAYER.WGCLAD

- bug fixes
- new coupler with less snapping errors
- adding Klayout generic DRC rule deck