1.2.1: Bugs fixes and UX improvements

Changelog

• Add keyboard control over footer items (up and down arrows to navigate through shortcut emojis, usertags, etc.) #209
• Add rel attribute to link-options* #210
• Fix multiple usertags display e36a217
• Open image preview on click #212
• Add audio-bit-rate & audio-sample-rateprops #217
• Fix nested formatted messages #213

*Credits to @natsumework