no need to cache hash lookups
sometimes singularize does not work, so we get a list of two strings. just uniq them
Moving add_column_options! up to SchemaCreation

removed two instances of add_column_options! from abstract_mysql_adapter

reworked rename_column_sql to remove add_column_options from schema_statements

changed to use new hash syntax.
Keep sub-second resolution when wrapping a DateTime value

Add `DateTime#usec` and `DateTime#nsec` so that `ActiveSupport::TimeWithZone`
keeps sub-second resolution when wrapping a `DateTime` value.

Fixes #10855
Add missing nsec test for 17f5d8e
Merge pull request #10425 from ranjaykrishna/push_add_column_options_to_schema_creation

Push add column options to schema creation