• Major refactoring of SQL::Translator::Diff again:
  
• Diff is no longer one huge monolithic function.
  
• Added more tests for diff
  
• When producing diffs for MySQL you will (by default) get single alter
  statements per table
  
• SQLite can also do remove columns (by creating a temp table as shown in
  http://sqlite.org/faq.html#q11
  
• Columns can be renamed if the new schema is from a form that can have metadata
  (which is pretty much anything but an SQL file.) It does this by looking at
  renamed_from in the $field->extra
  
• Updated Oracle and Postgres producers
  
• More tests!