pfSense

Following on from #4881

There are two minor issues in the NPt GUI when dealing with dynamic choices:

1. When there are multiple available entries the list isn't cleared and each line also contains the network of the previous line.

2. When picking a prefix entry from the drop-down the user is also forced to pick a matching prefix length even though the description in the drop-down lists the correct prefix length already. It should skip that check when choosing an entry from the list.