-code cleanup

-some documentation improvements
-README update

source/bubel/ecs/core.d

@@ -6,6 +6,7 @@ $(LIST
 	* Component: make component structure
 	* Event: make event structure
 )
+This mixins are optional and are used to adding some additional capabilities, e.g. ECS.System is used to configuring default number of jobs for system.
 
 ---
 Struct System1

source/bubel/ecs/manager.d

@@ -59,6 +59,9 @@ grouped by component type so entity can be fracted in big memory chunk.
 There is two types of update:
  - update(): function used to call update pass.
  - updateMT(): function used to call update pass multithreaded. This call only generates jobs which must be called by user.
+
+ WARNING! No fileds from EntityManager should be used directly, they are not private for special, advanced things which are not implemented in library.
+ So if you don't need anything special, simply use only EntityManager methods.
 */
 export struct EntityManager
 {
@@ -1611,11 +1614,6 @@ export struct EntityManager
         m_thread_id_func = cast(uint delegate() nothrow @nogc) get_id_callback;
     }
 
-    /*export void setJobDispachFunc(void delegate(JobGroup) @nogc nothrow func) nothrow @nogc
-    {
-        m_dispatch_jobs = func;
-    }*/
-
     /************************************************************************************************************************
     Return size of single page (block). Every entity data block has size of page.
     */
@@ -3762,20 +3760,6 @@ export struct EntityManager
             return 0;
     }
 
-    /*uint thread_id() @nogc nothrow
-    {
-        if (m_thread_id_func)
-            return (cast(uint delegate() nothrow @nogc) m_thread_id_func)();
-        else
-            return 0;
-    }
-
-    void thread_id(uint) @nogc nothrow
-    {
-    }*/
-
-    //static uint thread_id;
-
     ThreadData[] threads;
 
     Vector!(UpdatePass*) passes;