Wrong naming of snapshots in SETM, fixes #2915

rtgui/editorpanel.cc

@@ -567,6 +567,7 @@ void EditorPanel::open (Thumbnail* tmb, rtengine::InitialImage* isrc)
         Gtk::Allocation alloc;
         iareapanel->imageArea->on_resized(alloc);
     }
+    history->resetSnapShotNumber();
 }
 
 void EditorPanel::close ()

rtgui/history.h

@@ -126,6 +126,7 @@ public:
     void redo ();
 
     bool blistenerLock;
+    void resetSnapShotNumber() {bmnum = 1;};
 };
 
 #endif