Add block-editor support

Fixes #1 (closed), #5 (closed), #6 (closed), #7 (closed), #9 (closed), #10 (closed), #11 (closed), and #12 (closed)

assets/build/index.asset.php

+<?php return array('dependencies' => array('wp-components', 'wp-compose', 'wp-data', 'wp-edit-post', 'wp-element', 'wp-i18n', 'wp-plugins', 'wp-primitives'), 'version' => '6599c3d81e6a88ab5187');