export-main v0.0.1

A simple function exportMain(module, packageToExport) : packageToExport.
The function does just module.exports.default = module.exports = packageToExport.

⚠️ The function assign to the package's default field the package itself. Then: 1. The default field must be writable and not already used by another value, otherwise the value will be lost. 2. It creates a circle ref package.default = package (can be problem if you wish to serialize your package). 3. Doesn't work with primitives (String, Number & Boolean).