IFAD specific - add support for custom T_note_y(16) field in SchemaDumper

With these changes and the new https://github.com/ifad/sybase-schema-extractor we can execute tests against a local postgres install.
Instead of relying on the read only sybase db.

I suggest viewing this with ?w=1 flag - my vim indentation settings have made a bunch of whitespace changes.

Not sure exactly what the T_note_y field type is but it looks like something ifad specific. It caused exceptions with the default overridable AbstractAdapter prepare_column_options method. So I've done as suggested in that class and overridden this method.

We assume they are text columns.