Xcompact3d-toolbox

Fixed
- Fix 8, a little incompatibility problem with xcompact3d was fixed, by [fschuch](https://github.com/fschuch).

Added
- Add support for the previous parameters format `.prm` (7), by [fschuch](https://github.com/fschuch).
- Class `ParametersGui`, a subclass from `Parameters`, but with widgets, by [fschuch](https://github.com/fschuch).
- Argument `loadfile` added to class `Parameters`, so it is possible to initialize and load form the disc with just one line of code `prm = x3d.Parameters(loadfile='example.i3d')`, by [fschuch](https://github.com/fschuch).

Changed
- Changed from method `__call__` to `__repr__` at `parameters.py` as the procedure to show the parameters on screen, by [fschuch](https://github.com/fschuch).
- Functions to read binary fields were moved from `io.py` to methods at `parameters.py`, so the syntax is simplified from `x3d.read_field('filename', prm)` to just `prm.read_field('filename')`. by [fschuch](https://github.com/fschuch).

Fixed
- Scale factor for Ahmed Body at the sandbox, by [fschuch](https://github.com/fschuch).
- Fix 2, widgets are now working in a new class `ParametersGui`, by [fschuch](https://github.com/fschuch).
- Fix 5, Bug at Ahmed body when using double-precision, by [fschuch](https://github.com/fschuch).
- Fix 6, The files describing the geometry are incompatible when running on Linux, by [fschuch](https://github.com/fschuch).

Added
- `get_boundary_condition` at class `Parameters`. It returns the appropriate boundary parameters that are
expected by the derivative functions. by [fschuch](https://github.com/fschuch).
- First and second derivatives for stretched mesh in y, by [fschuch](https://github.com/fschuch).

Changed
- Syntax for `<da,ds>.x3d.simps` and `<da,ds>.x3d.pencil_decomp`. It is now possible to use them over multiple dimensions with just one call (for instance `ds.x3d.simps('x', 'y', 'z')`), by [fschuch](https://github.com/fschuch).

Fixed
- First derivative was incorrect when `ncl1=1` and `ncln=2`. by [fschuch](https://github.com/fschuch).

Fixed
- `param.mytype` was not updating properly [4](https://github.com/fschuch/xcompact3d_toolbox/issues/4), by [fschuch](https://github.com/fschuch).

Fixed
- BC parameters at ([param.py](xcompact3d_toolbox\param.py)), by [fschuch](https://github.com/fschuch).

Fixed
- [python-publish](.github/workflows/python-package.yml) action does not trigger if the release was first drafted, then published, by [fschuch](https://github.com/fschuch).