[sync] Patch for recurrence on Sync4j.php

[jochem at mondrian-it.nl]

The last couple of days, I've been testing my Windows Mobile PDA against the
horde syncml backend using the latest funambol plugin. I've noticed that
recurrence of the type 'daily, every weekday' in WM is handled differently
from kronolith. Kronolith assumes a daily item is supposed to happen every
day, whereas WM/Funambol/vCard assume a daily item works every day _unless_
the BYDAY or DayOfWeekMask values are set.

This means that when the WM recurtype 'daily, every weekday' was used,
kronolith also displayed it's items on Saturday and Sunday. This is ofcourse
not desirable.

I've been working with recurrence in Kronolith and vCal format for a
separate project of mine, and have come up with the attached patch to
SyncML/Devices/Sync4j.php to fix this bug.

I've tested this patch with both regular daily and weekday-daily recurrence,
and so far have not been able to break the new functionality.

Regards,

Jochem