Support JavaScript modules

- With modules JavaScript code can be split up into multiple files. We
	already implemented such a mechanism (`Engine.LoadLibrary`) in
	multiple parts of the engine. The advantage of using modules is
	that it's standart (JS-devs are familiar with it) and it doesn't
	has to be implemented multiple times.
	Note that `Engine.LoadLibrary` loads all files in a directory
	while the new `import` only loads one file.

- With modules seemingly global variables are local to that
	script/module. We already implemented such a mechanism
	(`ScriptInterface::LoadScript`).

binaries/data/mods/_test.scriptinterface/module/import_inside_function.js

@@ -0,0 +1,4 @@
+function foo()
+{
+	import "include/pi.js";
+}

binaries/data/mods/_test.scriptinterface/module/include/circle.js

@@ -0,0 +1,18 @@
+import { circleArea } from "include/geometry/area.js";
+
+class Circle
+{
+	radius;
+
+	constructor(radius)
+	{
+		this.radius = radius;
+	}
+
+	get area()
+	{
+		return circleArea(this.radius);
+	}
+}
+
+export default Circle;

binaries/data/mods/_test.scriptinterface/module/include/entry.js

@@ -0,0 +1,8 @@
+import RenamedCircle from "include/circle.js";
+
+const area = new RenamedCircle(10).area;
+
+if (area === (Math.PI * 100))
+	log("Test succeeded");
+else
+	throw new Error("Module Evalutation Error");

binaries/data/mods/_test.scriptinterface/module/include/geometry/area.js

@@ -0,0 +1,6 @@
+import importedPi from "include/pi.js";
+
+export function circleArea(radius)
+{
+	return importedPi * (radius * radius);
+}

binaries/data/mods/_test.scriptinterface/module/include/pi.js

@@ -0,0 +1 @@
+export default Math.PI;