Usability improvements

- Now entity.key() is the same as entity.key.value
- Entity:serialize only serializes component given correctly
- Any other value inside the Entity is ignored
- Disable some diagnostics used in Lua language server by sumneko

concord/builtins/key.lua

@@ -22,6 +22,10 @@ function Key:deserialize (data)
   self.value = getKey(self, data)
 end
 
+function Key.__mt:__call()
+  return self.value
+end
+
 function Key:removed (replaced)
   if not replaced then
     local entity = self.__entity