Clarify whether deleting a prefix deletes its children

[candlerb]

When I deleted a prefix, I wasn't sure whether it would delete child prefixes and child IP addresses or not. I was hoping it wouldn't, and relieved to find that was the case :-)

(Aside: what I was actually doing was turning a top-level container prefix into an aggregate)

To make this clear, I propose either:

1. Add some text to the delete confirmation page for Prefix, noting that child prefixes/addresses are not automatically deleted. (Might be worth doing this for Aggregate too); or

2. Add a new feature which lets you recursively delete child prefixes and addresses. Then, by not ticking this box, it's clear that you're only deleting the outer one. (Such a recursive delete would of course be highly dangerous, but may be useful)