K-9 Mail v5.400

• New widget: Message List
• Improved OpenPGP support
• New OpenPGP flow, adhering to Autocrypt specification
• Recipient search now includes nicknames
• Settings export uses Storage Access Framework
• Better support for multi-window
• Fixed bug that could cause OpenPGP signature verification to fail when it shouldn't
• Fixed bug that could lead to attachments not being displayed
• Fixed crash when encountering invalid email addresses
• Many more bugfixes and optimizations
• Updated translations
• Added translations: Albanian, Breton, Esperanto, Gaelic (Scottish), Icelandic, Indonesian, Welsh