Made a proper queued thread to client for handling some block mesh updates. Also made client mutex-free to allow easier adding of new stuff.

src/utility.h

@@ -1467,6 +1467,10 @@ protected:
 	core::list<T> m_list;
 };
 
+/*
+	A single worker thread - multiple client threads queue framework.
+*/
+
 template<typename Caller, typename Data>
 class CallerInfo
 {
@@ -1516,11 +1520,6 @@ public:
 	core::list<CallerInfo<Caller, CallerData> > callers;
 };
 
-/*
-	Quickhands for typical request-result queues.
-	Used for distributing work between threads.
-*/
-
 template<typename Key, typename T, typename Caller, typename CallerData>
 class RequestQueue
 {