Mailspring 1.20.0

What's new in this version:

Features:
- Added an "Automatic" theme (the new default) that follows system light/dark mode.
- Added system accent color support — the standard light and dark themes now use your OS accent color by default and this can be disabled from Preferences > Appearance
- Improved the UX around creating folders and labels in the left sidebar - it's much easier to create nested items
- A new "•••" menu on items in the left sidebar makes features (including the new EML export option) more discoverable.
- Added EML export functionality for messages and folders. You can save selected messages as EML by right-clicking or from the app's menu, and export entire folders by right clicking in the left navigation

Improved:
- Improved password storage error handling and reporting
- Fixed a race condition causing Windows notification "Archive" and "Mark as Read" buttons to be unreliable.
- Added Microsoft Office 365 / Outlook account setup guidance and troubleshooting documentation
- Replaced text symbols with SVG icons in the toolbar
- Refinements to EML export task in the sidebar.
- Fixed the Wayland app_id after Electron 41

Fixed:
- Fixed an undefined @font-weight-semi-bold error in the ui-less-is-more theme
- Fixed a crash in quick preview when the capture window is destroyed
- Fixed an unhandled EPIPE error when writing to a dead mailsync process stdin
- Fixed race conditions in draft expiration and changeset handling
- Fixed broken IMAP UTF-7 encoding by replacing the broken utf7 package with a custom implementation
- Fixed printToPDF errors being incorrectly sent to Sentry
- Fixed an issue where launch options and URLs were processed before app initialization was complete
- Fixed a crash caused by null values in draft field change detection
- Fixed an issue where metadata attachment could fail for newly sent messages
- Fixed autoupdate error handling
- Fixed error handling for ICS parsing in the EventHeader component
- Fixed crash when navigating to 'All' with accounts that have no archive category
- Fixed null reference crash in ContactDetail on update
- Fixed MacOS notifications showing a second copy of the app's icon
- Fixed null range crash in the email composer
- Fixed a race condition in EmailFrame that could deliver a null doc.body to message extensions
- Fixed OAuth code parsing to handle + characters correctly
- Fixed the core:pop-sheet shortcut being blocked in the message list with an open reply composer
- On Windows, fixed font-weight rendering by using CSS variables
- On Linux, fixed xdg-mime 'not found' error not being caught on dash-based shells
- Added error handling for shell.openExternal calls to prevent crashes on unsupported URLs

Developer:
- Fixed ability to declare platform-specific options via config-schema
- Moved appdata.xml to the metainfo directory for proper Linux packaging
- Replaced direct Electron dialog.showErrorBox calls with AppEnv.showErrorDialog
- Improved plugin activation error handling and TypeScript compilation
- Suppressed LESS parse errors from Sentry reporting