Gdsfactory

- improve tidy3d plugin
- add xmargin_left, xmargin_right, ymargin_bot, ymargin_top
- plot_simulation_xy and plot_simulation_yz
- fix materials
- add tests

- Explicit port serialization [PR](https://github.com/gdsfactory/gdsfactory/pull/178)
- difftest should fail when there is no regression reference [PR](https://github.com/gdsfactory/gdsfactory/pull/177)
- add Sparameters calculation in tidy3d plugin

- add progress bar to write_sparameters_lumerical_components

- modify the write_gds() function to fix the checking of duplicate cell names (recursively), and it also gives an option to choose how to handle duplicate cell names on write. It changes the default behavior to warn and overwrite duplicates, rather than throw an error. [PR](https://github.com/gdsfactory/gdsfactory/pull/174)
- remove clear_cache in `show()`. Intermediate clearing of cache can cause errors in final gds export, by leaving two versions of the same cell lingering within subcells created before/after cache clearing.
- remove clear_cache in some of the tests

- add `safe_cell_names` flag to gf.read.import_gds, append hash to imported cell names to avoid duplicated cell names.

- move triangle into requirements_dev.txt. Now that there is wheels for python3.9 and 3.10 you can manage the dependency with pip.