event registration information grouping

To post an event, the section that allow us to add registration information groups all registration variables in a single if clause using AND. This makes the possibility of displaying for example a registration link and leave out the remaining registration links difficult and also results in unwanted default text to be displayed

• A base-line suggestion: take out registration link as a separate option
  • since there are events we might need to announce that are hosted some where else(e.g. conferences we organize with other RSEs) and we only need to put a registration link and don't need to keep track of waiting list, or check if the event is booked out (which for the case of conferences I don't see this might be used), or unable to get registration period if the event has dynamic scheduling and is recurrent.