[ticket/12224] Add template wrapper method to assign block arrays

Add one more wrapper template method for the function assign_block_vars() which
takes a 2-dimensional array as a parameter
and calls assign_block_vars() in a loop to assign the whole block loop at once.
This can make the core a little bit more expendable from the point of
developing extensions as it allows to pass the data to events before
it's being assigned to template.

PHPBB3-12224

phpBB/phpbb/template/context.php

@@ -197,6 +197,22 @@ class context
 		return true;
 	}
 
+	/**
+	* Assign key variable pairs from an array to a whole specified block loop
+	*
+	* @param string $blockname Name of block to assign $block_vars_array to
+	* @param array $block_vars_array An array of hashes of variable name => value pairs
+	*/
+	public function assign_block_vars_array($blockname, array $block_vars_array)
+	{
+		foreach ($block_vars_array as $vararray)
+		{
+			$this->assign_block_vars($blockname, $vararray);
+		}
+
+		return true;
+	}
+
 	/**
 	* Change already assigned key variable pair (one-dimensional - single loop entry)
 	*