Scikit-rf

New Features
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- Voltages and currents can be extracted from Circuit 381 (see associated documentation: https://scikit-rf.readthedocs.io/en/latest/examples/circuit/Voltages%20and%20Currents%20in%20Circuits.html)

Documentation
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- Documentation Improvements 374:
- added various examples on how to create Network in tutorial documentation
- fix documentation on Media
- renamed media.circuit to media.device to avoid confusion with Circuit
- added media.device to the API documentation
- added many undocumented things to the API documentation:
- I/O (general, cvs, Touchstone, etc),
- constants
- NetworkSet
- plotting
- 358: add example on Mixed Mode S and Impedance Transformation.ipynb by jrmagers
- 382: Mention the 'traveling' option in the `s_def` option in the documentation

Bug corrections
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- 385: Don't shadow skrf's io module with the system io module by DanielO
- 378: Python 3.8 SyntaxWarnings 378 fixed by sxntxn
- 377: Plotted different mode gain instead of common mode gain 377 fixed by jrmagers
- 375: Fixes issue 369 on Numpy 1.19 behaviour
- 372: Correct the nrows calculation according to the proposal of cloidnerux in 366
- 365: add sorted in the `read_all()` in `general.py` 365 by xafra
- 364: remove unused matplotlib imports by JAnderson419
- 361: Fixed the bug reported by RF-NanoDetec in 360 in CPW Media and add tests
- 351: Fixed 2020 R2 HFSS Touchstone files reading

Bug Corrections
- Y-Smith chart labels fixed (Issue 347 solved by PR 348 )
- Touchstone 1.0 files data order fixed for 2 port networks (Issue 345 solved by PR 346 from sxntxn )
- `gamma` and `z0` data from HFSS Touchstone files fixed for large number of ports (Issue 350 solved by PR 351)
- fix bug related to kilo unit "k" (Issue 338 solved by PR 339 and 340 from DavidLutton and caleworkman)
- fix bug related to switch terms parsing (Issue 341 solved by PR 342, thanks to RF-NanoDetec )

New Features
- Noise deembedding features (PR 343 and 344 from FournierVincent, TomWoo and Gloamglozer). Additional features and documentation will arrive later.
- Add compatibility with HFSS version 2020R2 Touchstone files for `gamma` and `z0` data from (PR 351)

Documentation
- Add the [Slack channel link](http://scikit-rf.slack.com/) (PR #349 by JAnderson419 )
- New Documentation (PR 334, 337):
- [New `Circuit` tutorial](https://scikit-rf.readthedocs.io/en/latest/tutorials/Circuit.html)
- [New examples on matching from Pozar book (LC and stub)](https://scikit-rf.readthedocs.io/en/latest/examples/matching/Impedance%20Matching.html)
- [New .svg file containing Network symbols](https://github.com/scikit-rf/scikit-rf/blob/master/doc/source/skrf_Network_symbols.svg)
- Plus few smaller things

- fixed an issue (335 ) with Circuit when dealing with 1-port Networks
- added `networkx` to the list of conda dependendies

Summary:

- complex characteristic impedances (Issue 313, PR 320)
- connect port order changed (PR 289 and 330)
- suppressed some Numpy warning (PR 328)
- allow connect with frequency subsets (PR 300)
- bug fixes (322 324 326 )