ICS download fails in Safari on events without time set.

[RuthAdele]

I discovered today that if an event has no Start Time and/or End Time set (i.e. it goes all day), then the START_TIMESTAMP and END_TIMESTAMP end with a T, which causes the ICS download to fail in Safari.
I have written a very basic hack on my local copy as a quick fix (see below), but I thought you might want to come up with something a little nicer to fix the problem properly.

So in ICSLink() (line 127 of CalendarDateTime.php), I have used:
if ($this->obj('StartTime')->getValue()) {
$ics_start = $this->obj('StartDate')->Format('Ymd')."T".$this->obj('StartTime')->Format('His');
}
else {
$ics_start = $this->obj('StartDate')->Format('Ymd');
}
if($this->EndDate) {

if ($this->obj('EndTime')->getValue()) {
    $ics_end = $this->obj('EndDate')->Format('Ymd')."T".$this->obj('EndTime')->Format('His'); 
}
else {
    $ics_end = $this->obj('EndDate')->Format('Ymd'); 
}

}
else {
$ics_end = $ics_start;
}