- Make postgres name its enums
- Add way to filter columns by whether or not they're an enum
- Split parsing of enums into name & values
- Add strmangle check functions: IsEnumNormal, ShouldTitleCaseEnum
- Add new strmangle enum functions to template test
- Implement a set type called "once" inside the templates so that we can
ensure certain things only generate one time via some unique name.