* .prettierrc: full configuration for Prettier
This way, contributors using different-from-default settings will still
use the correct prettier settings
* Makefile: also lint .babelrc.js
* Makefile: also prettify .json files
* Exclude package.json files and correct build dir
* Add more default options to prettierrc and load it in cli
This avoids prettier looking up the config for each file
* Format json
* Update prettier and eslint and reformat codebase
* Remove obsolete file
* Add comment
