Rebuild add/edit forms as complete programmatic table/list templates

[Kris Deugau]

The add and edit pages are getting hairier to manage the more fields get added; if fine-grained ACLs ever get implemented this will only get worse.

Convert these templates to almost entirely generated form pages, based on a database table. Each row should include an ordering ID, primary label, and "form content" blob.

[Kris Deugau]

Much of the need for doing this has gone away with converting the alternating-colours layout to CSS instead of hardcoded per-row settings in r687. Adding a new row to various netblock-mangling pages will no longer require hand-fixing all of the following row colours.