Refactor the plugin demos to be inside of a project for convenience

plugins/addons/material_creator/material_plugin.gd

@@ -0,0 +1,23 @@
+# A simple (and silly) material resource plugin. Allows you to make a really simple material
+# from a custom dock, that you can save and load, and apply to selected MeshInstances.
+#
+# SPECIAL NOTE: This technically should be using EditorImportPlugin and EditorExportPlugin
+# to handle the input and output of the silly material. However, currently you cannot export
+# custom resources in Godot, so instead we're using JSON files instead.
+#
+# This example should be replaced when EditorImportPlugin and EditorExportPlugin are both
+# fully working and you can save custom resources.
+
+tool
+extends EditorPlugin
+
+var io_material_dialog
+
+func _enter_tree():
+	io_material_dialog = preload("res://addons/material_creator/material_dock.tscn").instance()
+	io_material_dialog.editor_interface = get_editor_interface()
+	add_control_to_dock(DOCK_SLOT_LEFT_UL, io_material_dialog)
+
+
+func _exit_tree():
+	remove_control_from_docks(io_material_dialog)