Cache format change possibly requires delete/rebuild local mail stores

[asctime]

In ba398ee local mail store and cache read-writes were changed to binary mode. First test indications confirm that this is a far more robust mechanic for Windows and the change-over was entirely beneficial. It will likely be kept and propagated through the rest of the codebase in further patches.

However, existing cache files and mail stores written using the previous ascii methods might experience minor corruption as CR/LF is no longer used for reading and writing them, thus require delete-and-rebuild. If you use remote IMAP, LDAP or CalDAV servers, new cache files from those services should generate automatically. For local stores, such as MBOX, MAILDIR, POP and local system calendars and contacts you can try exporting them remotely and re-importing them after upgrading or trying one of the many Ev2W file export/import options.

PLEASE BACK UP ALL ESSENTIAL LOCAL EV2W STORAGE BEFORE APPLYING THIS PATCH, AS A PRECAUTION.

Please post any feedback or questions related to Ev2W ascii-to-binary migrations or patches here.

[asctime]

Also recommended for b13cb23