Fixes:
- Figure out how to highlight email backgrounds when selected in list
- Refine view email page
-- Delete/read/unread/move actions that don't break everything
- Improve network status page
-- Show full network error? Make it copy-able?

Tasks:
- More layouts for intro and setup (tune for each screen size)
- Subclass EmailListFragment for each default mailbox
- Refactor code
-- Reorganize for clarity
-- Optimize use of Android lifecycles

Features:
- Public address book lookup
- Import/export identities
- Export Destination / make it copyable
-- SMS / message
- Add optional CC: and BCC: fields
- "Empty trash" option in Trash folder