This adds a few different fields to the column SQL builder that were
once either calculated or hard-coded:
* Import - so you can import the column from anywhere
* Type - fully, rather than partially, modifiable to allow any naming
convention
* TypeFactory - fully, rather than partially defined
I also alphabetized some things because the OCD compels me.
This change improves performance for generating mysql models
for databases with large number of tables. In my local testing
for a database with about 1000 tables and 140k columns, generation
time was reduced from about 1h to less than one second.
