add class() for easy definition of classes

code/entity.lua

@@ -1,6 +1,5 @@
 LoadedObjects.Entities = {}
-Entity = {}
-Entity.type = "Entity"
+Entity = class(nil, {type = "Entity"})
 
 function Entity:new(x,y)
 	local o = {}
@@ -26,7 +25,6 @@ function Entity:new(x,y)
 	o.sprite_flip = { x = 1, y = 1}
 
 	setmetatable(o, self)
-	self.__index = self
 	return o
 end