First working filters implementaton.

Only downstream filters are supported currently, i.e. no result
set filtering can be done.

A crude QLA (Query Log All) filter is included as a test harness only

server/include/modules.h

@@ -30,6 +30,7 @@
  * Date		Who		Description
  * 13/06/13	Mark Riddoch	Initial implementation
  * 08/07/13	Mark Riddoch	Addition of monitor modules
+ * 29/05/14	Mark Riddoch	Addition of filter modules
  * @endverbatim
  */
 
@@ -49,6 +50,7 @@ typedef struct modules {
 #define	MODULE_PROTOCOL	"Protocol"	/**< A protocol module type */
 #define	MODULE_ROUTER	"Router"	/**< A router module type */
 #define	MODULE_MONITOR	"Monitor"	/**< A database monitor module type */
+#define	MODULE_FILTER	"Filter"	/**< A filter module type */
 
 
 extern	void 	*load_module(const char *module, const char *type);