ESLint + Editorconfig

[toastal]

Here's my personal proposal for ESLint and Editorconfig with the aesthetic goal of blending established JavaScript standards with ergonomics slightly closer to PureScript:

With ESLint the base is eslint-config-standard which is quite common. With notable deviations:

• Dangling commas: reduces diff issues
• No spaces between function names and the (): nowhere in the current code seemed to be doing this
• Double quotes: matches PureScript better
• Spaces around values inside arrays and objects: matches purty's formatting of arrays and records for PureScript

Things the maintainer may want to adjust:

• Semicolons on (via semi: always): it seems semicolons were used more often than not, but it wasn't consistent and eslint-config-standard uses "never"
• Single quotes (remove the quotes block): single quotes seemed to be used more often, and while the JS community seems to have a favoritism towards singles, PureScript/Haskell/etc. use singles just for chars only which may not be the muscle memory for PureScript developers + strings 🤷‍.

Other changes caught by the linter:

• There were some "useless" escaped \. in the RegExps according to ESLint
• There was a loose != "" for an empty string.

To rerun+fix the linting if you were to make adjustments:

$ yarn lint:fix
# or
$ npm run lint:fix

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fixes #147