Implement remaining activity types

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/Activity/ChangeSet.php

@@ -28,6 +28,7 @@ class ChangeSet {
 
 	private $before;
 	private $after;
+	private $diff = false;
 
 	public function __construct($before = null, $after = null) {
 		if ($before !== null) {
@@ -38,6 +39,14 @@ class ChangeSet {
 		}
 	}
 
+	public function enableDiff() {
+		$this->diff = true;
+	}
+
+	public function getDiff() {
+		return $this->diff;
+	}
+
 	public function setBefore($before) {
 		$this->before = clone $before;
 	}