Feature
- Utilities to build trigger conditions based on field changes. [Wesley Kendall, 1471a35]
The following utility classes have been added to help trigger authors construct
trigger conditions based on changes to underlying fields:
- `pgtrigger.AnyChange`: If any supplied fields change, trigger the condition.
- `pgtrigger.AnyDontChange`: If any supplied fields don't change, trigger the condition.
- `pgtrigger.AllChange`: If all supplied fields change, trigger the condition.
- `pgtrigger.AllDontChange`: If all supplied fields don't change, trigger the condition.
A section in the docs was added for more examples on their use.