-changes in gitignore

-changed "absent" to "excluded" everywhere
-added Events support:
 *systems are scanned by handleEvent() function
 *generate system callers for events
 *event sending have (untested) multithreaded support
 *EventInput structure in System has input components for event

source/ecs/core.d

@@ -1,6 +1,7 @@
 module ecs.core;
 
 public import ecs.manager;
+public import ecs.entity;
 
 static struct ECS
 {
@@ -25,5 +26,6 @@ static struct ECS
     mixin template Event()
 	{
 		__gshared ushort event_id;
+		EntityID entity_id;
 	}
 }