Deprecate PHP entry point

Author: lucaswerkmeister

WikibaseImport.php

@@ -2,6 +2,11 @@
 
 if ( function_exists( 'wfLoadExtension' ) ) {
 	wfLoadExtension( 'WikibaseImport', __DIR__ . '/extension.json' );
+	wfWarn(
+		'Deprecated PHP entry point used for WikibaseImport extension. ' .
+		'Please use wfLoadExtension instead, ' .
+		'see https://www.mediawiki.org/wiki/Extension_registration for more details.'
+	);
 } else {
 	die( 'WikibaseImport requires MediaWiki 1.25+' );
 }