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.

scenes/item_select.tscn

@@ -0,0 +1,38 @@
+[gd_scene format=3 uid="uid://bslfk5as420f7"]
+
+[node name="ItemSelect" type="Control"]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+size_flags_vertical = 10
+metadata/_edit_use_anchors_ = true
+
+[node name="TabContainer" type="TabContainer" parent="."]
+layout_mode = 1
+anchors_preset = -1
+anchor_top = 0.830247
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 0
+metadata/_edit_use_anchors_ = true
+
+[node name="Zones" type="TabBar" parent="TabContainer"]
+layout_mode = 2
+
+[node name="ScrollContainer" type="ScrollContainer" parent="TabContainer/Zones"]
+layout_mode = 1
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+
+[node name="VBoxContainer" type="VBoxContainer" parent="TabContainer/Zones/ScrollContainer"]
+layout_mode = 2
+
+[node name="HBoxContainer" type="HBoxContainer" parent="TabContainer/Zones/ScrollContainer/VBoxContainer"]
+layout_mode = 2