Sometimes SQL errors occur when manipulating tables, some have been reported over here: #780358: Fix PK and index errors on table changes..

The underlying problem is that field specs, indexes and PKs can be changed for multiple fields at the same time.

We should at least:

- Create seperate add/remove index form.
- Create separate add/remove PK form.

But ideally also:

- Break out field spec form so that only spec can be changed at a time.