Allow to define notification type on AD_SchedulerRecipient

Users can define the way the system talk to them (NotificationType : EMail, Notice, Both, none).

When a scheduler is executed, recipients are informed according to their preferences.

But sometimes, you want to be sure that the user will have an email.
So, i propose to add NotificationType on AD_SchedulerRecipient. It would be non mandatory.
If empty, we use the user's preferences. Otherwise, we use what would be defined there.
I would prefer to put the list here (instead of AD_Scheduler) as it would be possible to force send email to a user and a notification to another one.

WDYT ?

Nicolas