Admin Page throws PHP error, Improve admin interface

First I need to issue my great thanks for this awsome module! A menu callback to an existing directory! Genius! Genius, I say! I can think of several scenarios where I'll use this technic in the future. But now... on to problems:

Right now the admin page throws a PHP error and has a lot of duplicate code in weird places (like a cut and paste gone horribly wrong). Hence the 'critical'. Beyond that issue, everything below is normal priority.

I've attached a patch which applies to the 4.7 branch. It makes numerous changes to admin side interface and behavior. Here's the complete list of changes:

Functional:
- Split up imagecache_admin_list function into proper form-handling functions (imagecache_admin_validate and imagecache_admin_validate). This eliminates the need to do check_plain() everwhere since the Forms API handles it all for us.
- Add a small amount of validation on ruleset names (only alphanumeric, _, and -)
- Removed auto_increment from DB schema, instead using the Drupal sequences table and db_next_id() (requires update.php run)

Visual:
- Drastic reduction of buttons and fields (screenshots to follow)
- Only one imagecache ruleset is displayed at a time (the one being edited/created)
- Added help text for imagecache actions menu

I think that covers the set of changes. I know that's a lot of changes all at once, but if I seperate it out the patches conflict with each other, so I thought it was better this way.

I'm using imagecache (or plan on using) for several high-volume sites, it's crucial that we make this module run butter-smooth. Thanks again! This module rocks!