Fix multi-calendar using & sync

Fix multi-calendar using & sync

With the new devices, we can have several calendar database. We have one
calendar per mails account.

If I sync calendar, it's OK the first time :
    1°/ a) Evolution : add a new event
        b) BlackBerry : empty (event isn't still knonw)
    2°/ run sync
    3°/ a) Evolution : event (no changement)
        b) BlackBerry : new event is added in the default calendar (OK)
    4°/ a) Evolution : edit the event
        b) BlackBerry : no modification
    5°/ run sync
    6°/ a) Evolution : event (no changement)
        b) BlackBerry : event is synced, but we loose the calendar link !

    6°/ b) => KO.

Other test case :
    1°/ a) Evolution : empty (event isn't still known)
        b) BlackBerry : add a new event associated to a mails account
    2°/ run sync
    3°/ a) Evolution : new event is added in the default calendar (OK)
        b) BlackBerry : event (no changement)
    4°/ a) Evolution : edit the event
        b) BlackBerry : no modification
    5°/ run sync
    6°/ a) Evolution : event (no changement)
        b) BlackBerry : event is synced, but we loose the calendar link !

To illustrate it :
+ Create calendar entry on the BlackBerry :
	Calendar entry: 0x5b17e358 (5)
	   All Day Event: no
	   Class: Public
	   Free/Busy: Busy
	   Subject: Test
	   Location: Home
	   Notification Time: Sat May 29 09:45:00 2010
	   Start Time: Sat May 29 10:00:00 2010
	   End Time: Sat May 29 11:00:00 2010
	   Recurring: no
		Unknowns:
			Type: 0x2a Data:
		00000000: 36 35 36 33 39 36 34 39 34 31 39 35 30 37 37 32  6563964941950772
		00000010: 30 35 35 00                                      055.
			Type: 0x2b Data:
		00000000: 64 71 2d 92 ec f0 93 bf                          dq-.....
	              <== seems to the calendar link
			Type: 0x2c Data:
		00000000: ff ff ff ff ff ff ff ff                          ........
			Type: 0x12 Data:
		00000000: 00 00 00 00                                      ....
			Type: 0x1b Data:
		00000000: 0c 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00  ................

+ Sync after Evolution editing :
	Calendar entry: 0x5b17e358 (5)
	   All Day Event: no
	   Class: Public
	   Free/Busy: Free
	   Subject: Test modif
	   Location: Home
	   Notification Time: Sat May 29 09:45:00 2010
	   Start Time: Sat May 29 10:00:00 2010
	   End Time: Sat May 29 11:00:00 2010
	   Recurring: no
		Unknowns:
			Type: 0x2a Data:
		00000000: 36 35 36 33 39 36 34 39 35 39 31 33 30 36 34 31  6563964959130641
		00000010: 32 34 33 00                                      243.
			Type: 0x2b Data:
		00000000: ff ff ff ff ff ff ff ff                          ........
	              <== information lost !
			Type: 0x2c Data:
		00000000: ff ff ff ff ff ff ff ff                          ........
			Type: 0x12 Data:
		00000000: 00 00 00 00                                      ....
			Type: 0x1b Data:
		00000000: 0c 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................

So, fix create a new CalendarID field "0x2b", by default is set to '-1'
and not used. If we detect that this field exists and is different to
'-1', we use this field (permit to compliant with old devices)