small fixes for command name loading

new readme with ref to github wiki
improve performance of command lookup.
Fix cmd type and object type in cached queries.
Support for MySQL 5.5.21 offsets

include/audit_handler.h

@@ -33,6 +33,7 @@ typedef struct _THDPRINTED {
 const char * retrieve_command (THD * thd);
 typedef size_t OFFSET;
 
+#define MAX_COM_STATUS_VARS_RECORDS 512
 
 /**
  * The struct usd to hold offsets. We should have one per version.
@@ -158,7 +159,7 @@ public:
         return thd->query;
 #endif
     }
-	//virtual char * retrieve_command (THD * thd);
+
 };