-some usefull functions for IDManager

-added EntityManager.removeEntity(EntityID)
-EntitiesBlock now has ID usefull for updating first_free_block in EntityInfo

source/ecs/system.d

@@ -5,15 +5,6 @@ import ecs.manager;
 
 struct System
 {
-    ///should system update and catch events?
-    bool m_enabled = false;
-    ///system priority
-    int prority;
-    ///pointer to system implementation
-    void* system_pointer;
-
-    uint[] components;
-
     bool enabled()
     {
         return m_enabled;
@@ -21,18 +12,34 @@ struct System
 
     void enable()
     {
-        if(!m_enabled && m_enable)m_enable(system_pointer);
+        if(!m_enabled && m_enable)m_enable(m_system_pointer);
         m_enabled = true;
     }
 
     void disable()
     {
-        if(m_enabled && m_disable)m_disable(system_pointer);
+        if(m_enabled && m_disable)m_disable(m_system_pointer);
         m_enabled = false;
     }
 
+    int priority()
+    {
+        return m_priority;
+    }
+
+package:
+
+    ///should system update and catch events?
+    bool m_enabled = false;
+    ///system priority
+    int m_priority;
+    ///pointer to system implementation
+    void* m_system_pointer;
+
+    uint[] m_components;
+
     //void function(ref EntityManager.CallData data, void* entity) update;
-    void* update; ///workaroud for DMD bug with upper line
+    void* m_update; ///workaroud for DMD bug with upper line
 
     void function(void* system_pointer) m_enable;
     void function(void* system_pointer) m_disable;