Essos

Similar release as before now with merged pull request of near-axis boundary.

What's Changed
* Merge Rj/nearaxis plotboundary by rogeriojorge in https://github.com/uwplasma/ESSOS/pull/7


**Full Changelog**: https://github.com/uwplasma/ESSOS/compare/v0.12...v0.13

Near-axis plotting working in new release.

**Full Changelog**: https://github.com/uwplasma/ESSOS/compare/v0.11...v0.12

**Full Changelog**: https://github.com/uwplasma/ESSOS/compare/v0.1...v0.11

This is the first release of ESSOS. Main functionalities are:
- optimization of coils for vmec surfaces
- optimization of coils for first order near-axis configurations
- optimization of coils and near-axis configurations at the same time
- trace fieldlines and particles in both guiding center and full orbit
- import and export coils/curves to/from SIMSOPT
- export to vtk/vtu/vts to see result in Paraview
- comprehensive unit tests
- read the docs page