Have a dialogue for backing up database before being converted

Whenever eM Client upgrade to a new version, the database also get converted for update to a new version. Before upgrading the database, a message should appear and warn about the conversion and suggest for a backup.

In newest versions eM Client will be also able to convert database back to the previous version if run with the previous version of eM Client (dialog will suggest the convert).

The backup feature is planned to one of the next versions. Meanwhile you need to backup the default database directory C:\Users\YourUsername\AppData\Roaming\eM Client (for Windows XP) or C:\Document and Settings\YourUsername\Application Data\eM Client to be sure.