Aiida-cp2k

- Add (optional) support for the AiiDA Gaussian Datatypes (104, 111).

- Fix docs build (102, 103)
- Advanced parser: parse electronic energy (108)

* Drop Python2 support. (95)
* Change docker base image to aiida-core. (96)
* Use BaseRestartWorkChain from aiida-core. (97)
* Enable dynamic outputs. (99)

Stable aiida-1.0 compatible relelase.

* Fix an issue with writing coordinates (52)

aiida-v1.0.0b4 compatible