Show Buttons in entity editor

- ScriptEngine: Added HasCustomAttribute- extension method
- ScriptEngine: Added Application class

ScriptCore/Editor/ShowInEditorAttribute.cs

@@ -7,11 +7,16 @@ namespace GlitchyEngine.Editor;
  * - this attribute also means that the Field is being serialized
  * - Editor-Namespace wont be available for distribution builds of the game
  */
+/// <summary>
+/// Specifies that the field should be visible in the editor, regardless of it's code visibility (private, protected, etc...)
+/// If this attribute is specified, the field will also be serialized.
+/// </summary>
 [AttributeUsage(AttributeTargets.Field)]
 public sealed class ShowInEditorAttribute : Attribute
 {
+    /// <summary>
+    /// The label with which the field will be shown in the editor.
+    /// If not specified, the fields name will be used.
+    /// </summary>
     public string DisplayName { get; set; } = null;
-
-    public ShowInEditorAttribute()
-    {}
-}
+}