FIxed GDC compilation (basic betterC WIP) and some improvements

-fixed issue with adding/removing entities inside events handling
-fixed EntityMeta.getComponent() (added check if component_id is valid)
-added function hasComponent to entity to check if component exists

tests/basic.d

@@ -5,7 +5,14 @@ import bubel.ecs.manager;
 import bubel.ecs.system;
 import bubel.ecs.attributes;
 
-import std.array : staticArray;
+version(GNU)
+{
+	pragma(inline, true) T[n] staticArray(T, size_t n)(auto ref T[n] a)
+	{
+		return a;
+	}
+}
+else import std.array : staticArray;
 
 struct CInt
 {