Release of v4.0.1-alpha4

Change the extendsinterfaces field to allow null, #1139. Update the Schema class to also update null mismatching if needed.

admin/sql/install.mysql.utf8.sql

@@ -367,9 +367,9 @@ CREATE TABLE IF NOT EXISTS `#__componentbuilder_power` (
 	`approved_paths` TEXT NULL,
 	`composer` TEXT NULL,
 	`description` TEXT NULL,
-	`extends` VARCHAR(36) NOT NULL DEFAULT '',
+	`extends` VARCHAR(36) NULL DEFAULT '',
 	`extends_custom` VARCHAR(64) NULL DEFAULT '',
-	`extendsinterfaces` TEXT NOT NULL,
+	`extendsinterfaces` TEXT NULL,
 	`extendsinterfaces_custom` TEXT NULL,
 	`guid` VARCHAR(36) NOT NULL DEFAULT '',
 	`head` TEXT NULL,