Content.module does not delete rows when deleting a single value field in some cases, and normalizing multivalue fields

Working on filefield.module I realized that content.module might work better if it knew whick fields needed to be deleted when updating multivalue fields...

I was having an issue where I would submit a file and errant values in node_field[$delta] would make content.module insert a new row in the field/content type table.

The existing approach is to just DELETE all the field data and reinsert for multivalues so any node_field[$delta] that is unset will disappear. I modified the code to delete if node_field[$delta] is null... So multivalue fields can set node_field[$delta] = NULL and content.module will be guaranteed to clean up.

To make a smaller set of code work more universally I also normalized how multivalue/single value fields were handled in the database... I decided to make an assumption that a delta column exists on all field tables... and work around that strategy. The net effect was the removal of a lot of conditional logic..
(I think there was some necessity to do this to make my targeted deletion stuff, but I lost it in a caffeine haze.)

the delta columns in the DB seem to behave well they reset themselves to 0 as necessary automagically.
I've tested with the stock field types, and things seem to be working properly... I can add content types and new fields without problem...

either way here is a patch to peruse.... you should only try it on fresh cck installs. I haven't written an update function yet. I wanted to bounce it off the other cck heads first.