base_calendar: convert libical timezones to plain format

Timezones sent to us by libical contain their prefix and thus wouldn't
match our preset list. Strip the prefix and try to match.

bzr revid: p_christ@hol.gr-20101015095652-mey4elruff8fv1y3

addons/base_calendar/base_calendar.py

@@ -1475,6 +1475,8 @@ true, it will allow you to hide the event alarm information without removing it.
             if not real_event_id in new_ids:
                 new_ids.append(real_event_id)
 
+        if vals.get('vtimezone', '').startswith('/freeassociation.sourceforge.net/tzfile/'):
+            vals['vtimezone'] = vals['vtimezone'][40:]
         if new_ids:
             res = super(calendar_event, self).write(cr, uid, new_ids, vals, context=context)
         if (vals.has_key('alarm_id') or vals.has_key('base_calendar_alarm_id'))\
@@ -1604,6 +1606,8 @@ true, it will allow you to hide the event alarm information without removing it.
         """
         if not context:
             context = {}
+        if vals.get('vtimezone', '').startswith('/freeassociation.sourceforge.net/tzfile/'):
+            vals['vtimezone'] = vals['vtimezone'][40:]
         res = super(calendar_event, self).create(cr, uid, vals, context)
         alarm_obj = self.pool.get('res.alarm')
         alarm_obj.do_alarm_create(cr, uid, [res], self._name, 'date', context=context)