Small improvements and fixed npm installer for Windows

Version 0.8.6 was not widely announced because of an issue with the npm installer on Windows,
so check the 0.8.6 release notes as well. Below are the additional changes in 0.8.7.

New features:

• case ... then is now auto-corrected to case ... of
• => is now auto-corrected to ->

Bug fixes:

• Top-level declarations named "infix" no longer make files unprocessable
• The npm installer should now work correctly on Windows (was broken for 0.8.6)

Install

npm install -g elm-format

or download from the release page.

Thanks to ...

• @kutyel for lenient parsing additions
• @emmabastas for the initial draft of test coverage scripts
• @jfmengels for continued thoughtful issue discussion across the Elm devtools community (only partially related to elm-format, but thank you!)
• @8n8 for code cleanup help
• Lamdera for providing CI runners to build the MacOS ARM64 release binaries