add history to equirect import

src/action.h

@@ -3,8 +3,9 @@
 class Action
 {
 public:
-    enum class Direction { Undo, Redo } m_direction;
+    enum class Direction { Undo, Redo } m_direction = Direction::Undo;
     bool was_saved = false;
+    Direction reverse_direction() const { return (Direction)(1 - (int)m_direction); }
     virtual void run() = 0;
     virtual void undo() = 0;
     virtual Action* get_redo() = 0;