Maskfill

This release primarily adds documentation, which can be found at [readthedocs](maskfill.readthedocs.io).

What's Changed
* make installable and import version by prappleizer in https://github.com/dokkum/maskfill/pull/1
* Updated Algorithm for Faster runtime, minor changes to install procedure by prappleizer in https://github.com/dokkum/maskfill/pull/2

New Contributors
* prappleizer made their first contribution in https://github.com/dokkum/maskfill/pull/1

**Full Changelog**: https://github.com/dokkum/maskfill/commits/v1.1.0-beta

Release upon submission of maskfill paper (van Dokkum 2023, PASP)