Sonic core v0.1.0

This release was focused on making improvements to search results
(see Milestone #20 “v1.7.x - Better search results (non-breaking)”).
We benchmarked the changes, and concluded the performance impact of all those
changes is negligible. If you notice something now being noticeably slower,
please tell us as it might be a bug!

Changes

• Implement proper case folding (in f67f964)
• Rework QUERY results ranking algorithm (see Pull Request #355 “No implicit AND”)
• Logging improvements
• More tests

New Features

• Allow disabling loose matching at the library level (in 17e196d)
• Add support for diacritics-insensitive search (in 3d38caa, 2379b0a)
• Add support for stemming (in db83731)

Bug Fixes

• Fix max typo correction in QUERY (in 097a752)
• config: Fix non-string parsing from env (in b17daad)