Slumba

Feature
* Support strings in scalar udfs but not in udafs ([`fe03e2f`](https://github.com/cpcloud/slumba/commit/fe03e2f97cdf0c383e9a09f529ef6425cdd95c0f))
* **strings:** Add support for reading strings ([`b6d74cb`](https://github.com/cpcloud/slumba/commit/b6d74cb13bdbec956d6d300166fddcaa70ff8687))

Feature
* **api:** Refactor api to use type annotations entirely ([`164a01a`](https://github.com/cpcloud/slumba/commit/164a01ac0232a956b70a7a387805cf38d811d3ac))

Breaking
* Type annotations must now be used to define both scalar and aggregate functions ([`164a01a`](https://github.com/cpcloud/slumba/commit/164a01ac0232a956b70a7a387805cf38d811d3ac))

Documentation
* More readme docs ([`48784b4`](https://github.com/cpcloud/slumba/commit/48784b499f214179124372ba83e5cba4afc36b5d))

Fix
* Return a new ref instead of a borrowed one ([`b9b3730`](https://github.com/cpcloud/slumba/commit/b9b37304555189f6fcbab5ebe1c0cdc658f13c86))
* Add missing exceptions.py module ([`5a1bfe0`](https://github.com/cpcloud/slumba/commit/5a1bfe0890a01f28658c8960ff5c8b9056760de5))
* Revert mypy ([`2ee28ca`](https://github.com/cpcloud/slumba/commit/2ee28cacfa5874f6b86a1457cb8a6d875c036aa5))
* Safely decref the pyobject that we use to store the state of agg initialization ([`fc70f1d`](https://github.com/cpcloud/slumba/commit/fc70f1d0038ef7eb2f529f5c7c5aeb57eb54e9da))
* Use reset_init in finalize to indicate that the next step call should reinit ([`3dc3d54`](https://github.com/cpcloud/slumba/commit/3dc3d5420e7cf6acd301170444d5a4746de54f97))
* Actually run constructors ([`8f02a99`](https://github.com/cpcloud/slumba/commit/8f02a99b42bb4cccfeae7c2851d70f8f4160b205))
* **udaf:** Compile __init__ functions ([`95fae29`](https://github.com/cpcloud/slumba/commit/95fae2952ee64b306c85246fe9b1aa21635d575e))

Breaking
* run constructors, which previously were not being called ([`8f02a99`](https://github.com/cpcloud/slumba/commit/8f02a99b42bb4cccfeae7c2851d70f8f4160b205))

Documentation
* Add some docs, comments and fix types ([`3f476bf`](https://github.com/cpcloud/slumba/commit/3f476bfcdf4415df3600a27f53a70f4c99262826))
* Comment more on how byref works ([`4ed4cf0`](https://github.com/cpcloud/slumba/commit/4ed4cf0bc71cc34908bb0117f8a8ca213962f50c))

Performance
* Tell mypy to ignore tests because it's way too slow ([`86a8b62`](https://github.com/cpcloud/slumba/commit/86a8b626f73794248f5e245ac57f9669734600a2))

Feature
* Add limited support for strings ([`13ed405`](https://github.com/cpcloud/slumba/commit/13ed4054a04eb2d3649bb56ada450821f30b6596))

Fix
* **numbaext:** Fix error message when encountering NULL values ([`b24ddd8`](https://github.com/cpcloud/slumba/commit/b24ddd863a9d29b7a3737e89c8dbb8df47fd9a5f))

Fix
* Raise an exception when a null is passed into a function that doesn't accept it ([`2304ef1`](https://github.com/cpcloud/slumba/commit/2304ef1f8b2f1691cd0686d895ef969348f9cc62))