Use JS classes for Template and Entity

`Template` and `Entity` used a costum form of inheritance.

Refs: #6285

binaries/data/mods/public/simulation/ai/common-api/class.js

@@ -1,20 +0,0 @@
-/**
- * Provides a nicer syntax for defining classes,
- * with support for OO-style inheritance.
- */
-export function Class(data)
-{
-	let ctor;
-	if (data._init)
-		ctor = data._init;
-	else
-		ctor = function() { };
-
-	if (data._super)
-		ctor.prototype = { "__proto__": data._super.prototype };
-
-	for (const key in data)
-		ctor.prototype[key] = data[key];
-
-	return ctor;
-}