* `--yesterday` is like `--today`, but for yesterday 😄.
* `--or` changes the behavior of filter criteria to return a union of
events matching an of the criteria than an intersection of events
matching all the criteria. Example:
ptk list --today --yesterday
Will never return results (because the criteria are mutually
exclusive).
ptk list --today --or --yesterday
Will return the marks for both today and yesterday.
Jonathan Bernard