Fix extension definitions

Before, extensions were missing the definition of mandatory methods.
At the moment, it's not a problem because the coding guidelines are not
enforced by the code. But in the future, it will break.
Now, extensions have all mandatory method definitions.

xExtension-QuickCollapse/extension.php

@@ -1,6 +1,17 @@
 <?php
 
 class QuickCollapseExtension extends Minz_Extension {
+	public function install() {
+		return true;
+	}
+
+	public function uninstall() {
+		return true;
+	}
+
+	public function handleConfigureAction() {
+	}
+
 	public function init() {
 		$this->registerTranslates();
 		$this->registerViews();