[olympic/studio] Move UndoCommand to its own file

src/olympic/studio/modlib/include/studio/studio.hpp

@@ -13,5 +13,6 @@
 #include <studio/popup.hpp>
 #include <studio/project.hpp>
 #include <studio/task.hpp>
+#include <studio/undocommand.hpp>
 #include <studio/undostack.hpp>
 #include <studio/widget.hpp>

src/olympic/studio/modlib/include/studio/undocommand.hpp

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2016 - 2024 Gary Talent (gary@drinkingtea.net). All rights reserved.
+ */
+
+#pragma once
+
+namespace studio {
+
+class UndoCommand {
+	public:
+		virtual ~UndoCommand() noexcept = default;
+		virtual void redo() noexcept = 0;
+		virtual void undo() noexcept = 0;
+		[[nodiscard]]
+		virtual int commandId() const noexcept = 0;
+		virtual bool mergeWith(UndoCommand const*cmd) noexcept;
+};
+
+}

src/olympic/studio/modlib/include/studio/undostack.hpp

@@ -9,17 +9,9 @@
 #include <ox/std/memory.hpp>
 #include <ox/std/vector.hpp>
 
-namespace studio {
+#include "undocommand.hpp"
 
-class UndoCommand {
+namespace studio {
-	public:
-		virtual ~UndoCommand() noexcept = default;
-		virtual void redo() noexcept = 0;
-		virtual void undo() noexcept = 0;
-		[[nodiscard]]
-		virtual int commandId() const noexcept = 0;
-		virtual bool mergeWith(UndoCommand const*cmd) noexcept;
-};
 
 class UndoStack {
 	private: