Submit package to packagist

There is a composer.json file now, but the package isn't available on packagist so adding a 'repository' object to the root composer.json is required.

May want to consider reorganizing the code into PSR-4 format as well.

Start with the root composer.json and inspect the package metadata and current code layout. Verify what Packagist requires for this repository, then check whether the optional PSR-4 reorganization is in scope. Done means the package is available on Packagist and any agreed autoloading changes are reflected consistently.

Written by the indexing model from the issue text.