Speedyfit

Bugfixes:
- fixed the "FutureWarning: Using a non-tuple sequence for multidimensional indexing is deprecated" issue in interpol.create_pixeltypegrid().
- updated the nonposx and nonposy keyword arguments in plt.set_xscale/plt.set_yscale to nonpositive to match the new versions of matplotlib.
- The newest version of corner plot can't display more than 3 quantiles. So If no quantiles are set, we show the default 0.16, 0.5, 0.84 quantiles instead of [0.025, 0.16, 0.5, 0.84, 0.975].

Feature:
- More work on batch fits: added support for constraints and code improvements. Not completely finished yet.

Bugfix: If the SPEEDYFIT_MODELS folder contained spaces, speedyfit could not find the model fits files. This is now fixed. Also extended the warnings for when models can not be found.

Other: added version requirements for pyvo and astropy because older pyvo versions don't work with new astropy versions.

Feature: Added more convenient option for the user to modify the photometry catalog files. The catalogs can now be copied to the SPEEDYFIT_MODELS directory and modified there by the user. Speedyfit will first look into that directory when looking for the catalogs files and only if it can't find them, it will use the catalogs shipped with the package.

Bugfix: Fixed issue where the user had to add a trailing '/' to the SPEEDYFIT_MODELS env var. Now os.path.join is used to create filepaths so there is no issue on whatever system it is used.

Docs: Some improvements in the documentation were made.

Updated the skymapper url in the tap catalogue list as that service dropped support for http.

Features:
- Added support for Gaia EDR3, both for parallaxes and photometry
- Added automatic calculation of parallax zero point offset based on Lindgren 2020
- Added functionality to integrate model atmosphere grids
- Included transmission curves for most common photometric systems in the package

Other:
- Some code refactoring
- Added some examples in the code to integrate atomspheric model grids

Documentation: Still a work in progress.

Feature: added option to check which grids are available as a command line option instead of an api function. (API function remains as well.)

Documentation: Updated documentation with new command line option and added documentation on how to add new grids to speedyfit.