Fastmail Plus per SK

Fastmail Plus makes Fastmail (https://fastmail.com) web UI easier to use and more productive.

Features:
- Change focus using ↑ ↓ ← → cursor keys
- Badge notification for unread messages to Inbox
- Faster switch between different search modes
- Easier button operation in reading pane
- Extra shortcut keys (Press ? key to show available shortcut keys)
- Fix problem with Japanese IME in default search input
- Extra "reply-to" folding
- Maximize width
- Light/Dark theme support

If you have any ideas or proposals, feel free to reach out on github or on twitter.

https://www.twitter.com/5katkov