davmail: 4.6.1 -> 4.7.0

Upgrade message: http://sourceforge.net/p/davmail/mailman/message/34597887/

This new release contains a lot of fixes from user feedback, a new
-notray command line
option to force window mode and avoid tricky tray icon issues on Linux
and native
smartcard support on Windows.

Caldav:
- Caldav: Map additional priority levels
- Caldav: fix missing LAST-MODIFIED in events

Enhancements:
- Improved tray icon with alpha blend
- Fix imports
- Prepare mutual SSL authentication between client and DavMail
implementation
- Implement -notray command line option as a workaround for broken SWT
and Unity issues
- Change warning messages to debug in close method
- Improve client certificate dialog, build description from certificate
- Exclude client certificates not issued by server provided issuers list

IMAP:
- IMAP: Additional translations and doc for new IMAP setting
- IMAP: Merge patch by Mauro Cicognini, add a new setting to always send
approximate message in RFC822.SIZE to avoid downloadi...