How to use global_calendar
==========================
by Thomas Chung <tchung@openwebmail.org>
on 2010.11.18

1. Create an account to manage global calendar.
   For example, I've created an account called "calmanager" 
 
2. Login as calmanager and create an event.
   This way "calendar.book" file will be created in calmanager's webcal directory.
   /home/calmanager/.openwebmail/webcal/calendar.book

3. Replace global calendar.book file with calmanager's calendar.book file 
   # cd /var/www/cgi-bin/openwebmail/etc
   # cp /home/calmanager/.openwebmail/webcal/calendar.book .
   cp: overwrite `./calendar.book'? y

4. Create a symlink to global calendar file from calmanger's webcal directory.
   # cd /home/calmanager/.openwebmail/webcal/
   # ln -sf /var/www/cgi-bin/openwebmail/etc/calendar.book

5. Make sure to change ownership of the global calendar.book file to calmanager
   # chown calmanager:calmanager /var/www/cgi-bin/openwebmail/etc/calendar.book

6. Create another event from calmanager and verify it from another account.