Add block-editor support

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

tests/bootstrap.php

@@ -5,7 +5,7 @@
  * @package Automatically_Paginate_Posts
  */
 
-$autopaging_tests_dir = getenv( 'WPautopaging_tests_dir' );
+$autopaging_tests_dir = getenv( 'WP_TESTS_DIR' );
 
 if ( ! $autopaging_tests_dir ) {
 	$autopaging_tests_dir = rtrim( sys_get_temp_dir(), '/\\' ) . '/wordpress-tests-lib';