Wake-t

Minor release mostly with bug fixes.
What's Changed
* openPMD-api: No Upper Limit by ax3l in https://github.com/AngelFP/Wake-T/pull/116
* Change input parameters of ramp profiles by AngelFP in https://github.com/AngelFP/Wake-T/pull/117
* Fix bug in grid global offset introduced in (69) by AngelFP in https://github.com/AngelFP/Wake-T/pull/118
* Allow laser envelope time step to change by AngelFP in https://github.com/AngelFP/Wake-T/pull/119
* Avoid using latest numba release by AngelFP in https://github.com/AngelFP/Wake-T/pull/121
* Fix and update documentation by AngelFP in https://github.com/AngelFP/Wake-T/pull/120
* Raise `RuntimeError` for numba 0.57.0 by AngelFP in https://github.com/AngelFP/Wake-T/pull/122


**Full Changelog**: https://github.com/AngelFP/Wake-T/compare/v0.6.0...v0.6.1

What's Changed
* Implement Boris pusher. by jorgesantin28 in https://github.com/AngelFP/Wake-T/pull/66
* Implement new `Tracker` class by AngelFP in https://github.com/AngelFP/Wake-T/pull/76
* Implement 5th order Adams-Bashforth pusher by AngelFP in https://github.com/AngelFP/Wake-T/pull/77
* Improve performance of Baxevanis wakefield model by AngelFP in https://github.com/AngelFP/Wake-T/pull/79
* Implement new tracking pipeline by AngelFP in https://github.com/AngelFP/Wake-T/pull/69
* Implement numba caching and custom decorators by AngelFP in https://github.com/AngelFP/Wake-T/pull/80
* Improve openPMD diagnostics by AngelFP in https://github.com/AngelFP/Wake-T/pull/81
* z injection by delaossa in https://github.com/AngelFP/Wake-T/pull/82
* Progress bar improvements by AngelFP in https://github.com/AngelFP/Wake-T/pull/84
* Fix plasma deposition bug by AngelFP in https://github.com/AngelFP/Wake-T/pull/85
* Enable laser envelope solver subcycling by AngelFP in https://github.com/AngelFP/Wake-T/pull/86
* Add support for simulations with multiple (or no) bunches by AngelFP in https://github.com/AngelFP/Wake-T/pull/87
* Implement base `RZWakefield` class by AngelFP in https://github.com/AngelFP/Wake-T/pull/88
* Improve efficiency of envelope solver by AngelFP in https://github.com/AngelFP/Wake-T/pull/89
* Subgrid envelope by delaossa in https://github.com/AngelFP/Wake-T/pull/90
* Splits a line which was too long for flake8 by delaossa in https://github.com/AngelFP/Wake-T/pull/91
* Enable laser envelope to run in a subgrid by AngelFP in https://github.com/AngelFP/Wake-T/pull/92
* Replace old Travis badge with GitHub actions by AngelFP in https://github.com/AngelFP/Wake-T/pull/93
* Make use of complex envelope phase optional + allow `Field` instances as `wakefield_model` by AngelFP in https://github.com/AngelFP/Wake-T/pull/97
* Implement non centered envelope solver for laser initialization by AngelFP in https://github.com/AngelFP/Wake-T/pull/98
* Improve performance of envelope solver by AngelFP in https://github.com/AngelFP/Wake-T/pull/99
* Fix precision issue in calculate_ai_bi_from_axis and calculate_ai_bi_from_edge by AlexanderSinn in https://github.com/AngelFP/Wake-T/pull/101
* Field element by AngelFP in https://github.com/AngelFP/Wake-T/pull/102
* Add openPMD viewer test by AngelFP in https://github.com/AngelFP/Wake-T/pull/103
* Improve documentation and add type hints by AngelFP in https://github.com/AngelFP/Wake-T/pull/107
* Small fixes to docstrings by AngelFP in https://github.com/AngelFP/Wake-T/pull/108
* Add support for non-electron bunches by AngelFP in https://github.com/AngelFP/Wake-T/pull/109
* Fix test output by AngelFP in https://github.com/AngelFP/Wake-T/pull/110
* Fix section title in the documentation by AngelFP in https://github.com/AngelFP/Wake-T/pull/111
* Fix laser envelope amplitude by AngelFP in https://github.com/AngelFP/Wake-T/pull/112

New Contributors
* jorgesantin28 made their first contribution in https://github.com/AngelFP/Wake-T/pull/66
* AlexanderSinn made their first contribution in https://github.com/AngelFP/Wake-T/pull/101

**Full Changelog**: https://github.com/AngelFP/Wake-T/compare/v0.5.1...v0.6.0

Minor release including improvements to reading particle beams from openPMD files.

What's Changed
* Improve default behavior of openPMD particle reader by AngelFP in https://github.com/AngelFP/Wake-T/pull/72


**Full Changelog**: https://github.com/AngelFP/Wake-T/compare/v0.5.0...v0.5.1

New Contributors
* ax3l made their first contribution in https://github.com/AngelFP/Wake-T/pull/13
* delaossa made their first contribution in https://github.com/AngelFP/Wake-T/pull/19
* wdenhertog made their first contribution in https://github.com/AngelFP/Wake-T/pull/24
* rob-shalloo made their first contribution in https://github.com/AngelFP/Wake-T/pull/31
* MaxThevenet made their first contribution in https://github.com/AngelFP/Wake-T/pull/45

**Full Changelog**: https://github.com/AngelFP/Wake-T/compare/v0.4.0...v0.5.0

This new release brings `Wake-T` to version `0.4.0`. The main focus is on the new 2d quasistatic wakefield model from [P. Baxevanis and G. Stupakov](https://journals.aps.org/prab/abstract/10.1103/PhysRevAccelBeams.21.071301), which greatly expands the capabilities of `Wake-T`.

This model allows for the accurate calculation of plasma wakefields in the blowout and strongly non-linear regimes, which were not previously accessible (due to limitations of the 1d non-linear fluid model). It can also compute the wakefieds from the witness beam (and not only the driver), meaning that beam-loading effects are now fully taken into account.

With respect to the original publication by Baxevanis and Stupakov, the model has here been extended to include laser-driven wakefields. In addition, it can now also compute the beam wakefields from full particle distributions and not just from analytical gaussian beam expressions.

A comparison between the wakefields as obtained from [`FBPIC`](https://github.com/fbpic/fbpic) simulations with the new quasistatic model in `Wake-T` can be seen below.


Changelog
* New quasistatic wakefield model added. Can be used by specifying `wakefield_model='quasistatic_2d'` in the `PlasmaStage`, `PlasmaRamp` and `PlasmaLens` elements.
* Added beam wakefields to `PlasmaLens`. For this, a new class `CombinedWakefield` has been implemented.
* Beam loading effects can now also be taken into account in `cold_fluid_1d` model by setting `beam_wakefields=True` in `PlasmaStage` and `PlasmaRamp` elements.
* Simulations with no laser (i.e. with only a particle beam) can now be performed.
* Increased performance of Runge-Kutta solver by using `numba` for some calculations.
* Changed from `RegularGridInterpolator` to faster interpolation with `RectBivariateSpline`.
* Changed to a much faster way of computing the `sin` and `cos` of the particle `theta` in cylindrical coordinates.
* Changed `driver` keyword to `laser` for the wakefield models.
* Updated existing example and created new one for quasistatic model.
* Updated `README.md` to remove beam-loading limitation.
* Added `numba` as requirement.
* `Wake-T` is now installed as part of the CI tests.
* Removed `gamma` input parameter from `Wakefield` methods.
* Increase version to number to `0.4.0`.

This release focuses on consolidating and uniformizing the structure of the beamline elements and adds a 1D CSR model.

Changelog:
* Drifts are now also tracked using transfer matrices up to order 2.
* The properties of all elements are now set in the constructor. For the plasma stages this now includes the tracking mode (analytical or numerical) as well as the wakefield model used.
* All elements now feature a single `track` method. Previously different elements had different, or even several tracking methods.
* A `Beamline` class has been added which simplifies particle tracking along several elements.
* The implementation of second-order tracking is now significantly more efficient.
* A 1D CSR model has been added. It is based on an adapted and streamlined version of the 1D model found in Ocelot. A sample simulation for a 1 nC beam after a chicane is shown below:

<p align="center">
<img alt="csr_off" src="https://user-images.githubusercontent.com/20479420/80230878-d2c83d80-8652-11ea-9046-77b8845c3b3a.png" width="350px" />
<img alt="csr_on" src="https://user-images.githubusercontent.com/20479420/80230893-d956b500-8652-11ea-9ae0-78121dd19a49.png" width="350px" />
</p>

* Several bug fixes and other internal changes.