Mostly bugfix update + empty components support and remove EntityID from Event structure

-empty components now take no memory, so flag components is now far better
-added test for critical bug
-fixed critical bug with adding/removing entities form inside events
-fixed small bug with TestRunner
-improve basic tests
-fixed betterC compilation on DMD
-remove EntityID form Event structure
-added "return" attribute to some functions
-moved some code from Tempalte side to actual implementation
-fixed bug with EntityTemplate copying
-commented out some possibliy unused code
-use code formatter

source/bubel/ecs/core.d

@@ -75,19 +75,18 @@ static struct ECS
 	{
 		__gshared ushort component_id = ushort.max;
 
-		ComponentRef ref_() @nogc nothrow
+		ComponentRef ref_() @nogc nothrow return 
 		{
-			return ComponentRef(&this,component_id);	
+			return ComponentRef(&this, component_id);
 		}
 	}
 
 	/************************************************************************************************************************
 	Mark structure as Event. Should be added on top of structure (before any data).
 	*/
-    mixin template Event()
+	mixin template Event()
 	{
 		__gshared ushort event_id = ushort.max;
-		EntityID entity_id;
 	}
 
 	/************************************************************************************************************************
@@ -113,4 +112,4 @@ static struct ECS
 	{
 		alias WritableDependencies = T;
 	}
-}
+}