Start of edit mode scripts

- Initialize script instances in edit mode
- Run OnCreate and OnUpdate for Entities with RunInEditMode-Attribute

ScriptCore/Editor/RunInEditModeAttribute.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace GlitchyEngine.Editor;
+
+/// <summary>
+/// Specifies that the OnCreate- and OnUpdate-Methods of this entity are to be be executed in the editor.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class)]
+public sealed class RunInEditModeAttribute : Attribute
+{
+}