Prevent endless loops and long running feed processing

static/defaults.config.php

@@ -273,6 +273,10 @@ return [
 		// Maximum number of queue items for a single contact before subsequent messages are discarded.
 		'max_contact_queue' => 500,
 
+		// max_feed_items (Integer)
+		// Maximum number of feed items that are fetched and processed. For unlimited items set to 0.
+		'max_feed_items' => 10,
+
 		// max_image_length (Integer)
 		// An alternate way of limiting picture upload sizes.
 		// Specify the maximum pixel  length that pictures are allowed to be (for non-square pictures, it will apply to the longest side).