Fixes:
- Auto-comma the To: field when it loses focus
- Fix tick over selected emails
- Delete/read/unread/move actions on view email page that don't break everything

Tasks:
- Show logged-in status in persistent notification
- Intro and setup
  - More layouts (tune for each screen size)
  - Wording
    <zzz> The only thing that sounded odd was talking about encryption "on-disk" which is very odd for a phone or tablet. I'd say "on your device" or something similar.
- Subclass EmailListFragment for each default mailbox
- Cache Identicons for speed
- Refactor code
  - Reorganize for clarity
  - Optimize use of Android lifecycles

Features:
- Fingerprints that users can compare to validate
- Public address book lookup
- "Write email" link in address book
- Add optional CC: and BCC: fields
- Attachments
- "Empty trash" option in Trash folder
- Overlay to explain
- Option to run only when connected to an outlet
- Option to run only when connected to wifi