Update version number and applications
Create README.md
Add a minimum size to the preview box
Catch filename param from imap:// URLs
Add logging to compose.js
Don't display a notification if there is one already
Tidy log messages and emit filename and line numbers when logging
Remove Shrunked.imageLargerThanThreshold because it is useless
Update version number to 3.2.1
Add context menu item for compose window
Refactoring and code tidy in compose.js