Release v1.2.0

What's Changed

• fix #9 by @zplus11 in #10
• introduce a chain complex object by @zplus11 in #13
• Fixes by @zplus11 in #14
• Feature/integrate chain complexes by @zplus11 in #16
• Docs/update citation by @zplus11 in #17
• duplicates check in facets (fixes #11) by @zplus11 in #18
• Minor cleanup by @zplus11 in #19
• fix some formatting and error handling by @zplus11 in #21
• Feature/test suite by @zplus11 in #22
• Prepare/v1.2.0 by @zplus11 in #23

Full Changelog: v1.1.1...v1.2.0