v2.2.0

Style, layout, and icon improvements, implementation of box zoom, line analysis plugin enhancement, JWST cube data bugfix. See changelog for details.

What's Changed

• Put changelog back in unreleased state by @rosteen in #1000
• DOC: Add milestone bookkeeping by @pllim in #1001
• update colors of top toolbar and import button by @kecnry in #1007
• BUG: Recreate JWST MJD-OBS if it is missing by @pllim in #1004
• consistent plugin padding & styling by @kecnry in #1008
• plot toolbar icons and styling by @kecnry in #995
• implement box zoom by @kecnry in #997
• Line analysis subsets by @rosteen in #1012
• Prep changelog for 2.2.0 release by @rosteen in #1016

Full Changelog: v2.1.0...v2.2.0