Metakernel

- Combine `exec`/`eval` evaluators [213](https://github.com/Calysto/metakernel/pull/213) ([joequant](https://github.com/joequant))
- Dev/fix `voila` [212](https://github.com/Calysto/metakernel/pull/212) ([joequant](https://github.com/joequant))
- Add `Error_display` method to `_metakernel.py` [205](https://github.com/Calysto/metakernel/pull/205) ([jld23](https://github.com/jld23))

- Fix python evals 208 [210](https://github.com/Calysto/metakernel/pull/210) ([joequant](https://github.com/joequant))
- Fix `ipywidgets` display [209](https://github.com/Calysto/metakernel/pull/209) ([joequant](https://github.com/joequant))

- Remove undefined line in expect stdin 203 [204](https://github.com/Calysto/metakernel/pull/204) ([dekuenstle](https://github.com/dekuenstle))
- Add `portalocker` and `ipyparallel` as optional dependencies [202](https://github.com/Calysto/metakernel/pull/202) ([mdeff](https://github.com/mdeff))

- Update `activity_magic.py` [197](https://github.com/Calysto/metakernel/pull/197) ([dovfields](https://github.com/dovfields))

- Fix `TypeError` [192](https://github.com/Calysto/metakernel/pull/192) ([ellert](https://github.com/ellert))

- Delay creating wrapper until we need to execute [190](https://github.com/Calysto/metakernel/pull/190) ([blink1073](https://github.com/blink1073))