calendar common location

[Rodrigo Moya <rodrigo gnome-db org>]

Hi

Talking about the calendar/contacts common location with other evolution
hackers, some issues have arised.

* would events and tasks be stored in separate files? what about
VJOURNAL components?

* there needs to be a defined locking mechanism for calendar/contact
files, so that concurrent access can be done to the files. If not, we
risk to lose information if 2 or more apps happen to be accessing the
same file at the same time.

cheers