0.2.6

* Use `Integral` not `Int`.
* `Digits` data type (zero or many digits) and associated functions.

0.2.5

* Change parser to handle non-empty list.

0.2.4

* More Digit parsers.

0.2.3

* Digit parsers.

0.2.2

* Modulus operations.
* `digits` function.
* Fix tests.

0.2.1

* Include digit parsers.

0.2.0

* Update to use digit prisms.