Changes since v0.1.8:

* add the `hasHole` and `isComplete` functions
* add the `encompasses` function
* add `appendInt` to `Data.Express.Fixtures`
* add the `u-conjure` example
* the `Express` typeclass now requires `Show`
* improve examples in the `eg/` folder
* improve tests of `hasInstanceOf` and `isInstanceOf`
* improve tests
* add a changelog