Added
- Support for `not:pri:`, which was kind-of implied in the documentation, but not really implemented yet
- Support for relative dates in searches for `due:` (and before/after), `created:` (and before/after), and `completed:` (and before/after), which was already promised in the documentation but didn't fully work (and when it did, it was horribly inefficient)
Fixed
- Implementation for `lessimportant:` and `moreimportant:` was broken ([13](https://github.com/vonshednob/pter/issues/13))