don't merge actions that have been undone before, for example:

typing1 Ctrl+Z Ctrl+Y typing2 Ctrl+Z
removes just typing2, not both.

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@1323 0fc631ac-6414-0410-93d0-97cfa31319b6

src/util/action_stack.hpp

@@ -114,6 +114,8 @@ class ActionStack {
 	vector<Action*> redo_actions;
 	/// Point at which the file was saved, corresponds to the top of the undo stack at that point
 	Action* save_point;
+	/// Was the last thing the user did addAction? (as opposed to undo/redo)
+	bool last_was_add;
 	/// Objects that are listening to actions
 	vector<ActionListener*> listeners;
 };