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/package.d

@@ -7,4 +7,4 @@ public import bubel.ecs.system;
 
 import bubel.ecs.events;
 import bubel.ecs.id_manager;
-import bubel.ecs.std;
+import bubel.ecs.std;