Major clean up and reorganization

- Upgraded to Godot 4
- Just remembered the basic principles are based on a tile editor, and dramatically simplified from there. Derp.
- New state machine and license display add-ons.
- Re-licensed under the GPL because Micropolis' assets aren't under a separate one.

licenses/license_links/SimpleLicense.tres

@@ -0,0 +1,14 @@
+[gd_resource type="Resource" script_class="LicenseLink" load_steps=3 format=3 uid="uid://d2b7iusbtenmi"]
+
+[ext_resource type="Script" path="res://addons/simplelicense/api/LicenseLink.gd" id="1_3or5k"]
+[ext_resource type="Script" path="res://addons/simplelicense/plugin.gd" id="1_qarv5"]
+
+[resource]
+script = ExtResource("1_3or5k")
+link_files = Array[Resource]([])
+link_dirs = Array[Resource]([ExtResource("1_qarv5")])
+link_paths = []
+componet_name = "Simple License"
+extra = ""
+license_identifier = "CC0-1.0"
+copyright = Array[String](["2023, GradyTheDev"])