bump version to 3.1.2 (to fix packaging error)

morebits: quickform: handle undefined label

fixes for proper JS/TS-agnostic import from twinkle-starter

- Don't use type=module in package.json as this is resulting in issues with Webpack. Use CommonJS require() syntax in all node scripts
- Build JS files to `js` directory. Don't emit declarations.
- Remove main and types fields from package.json. This means that code like `import ... from 'twinkle-core'` no longer works. Import must necessarily mention the path, which is different depending on the whether JS is being used or TS.

package.json: add lib to file list; add chalk devDep

package.json: fix file paths

try to fix versiondocs workflow

clarify contributing tips; bump version

misc updates