Minor UI improvments & bugfixes

- improved "Copy text" option in right click menu, to display what exactly to copy
- added "Dump selected assets" option to right click menu
- added 'selected assets count' info to status strip when you select assets
- added 'exported count / total export count` info to status strip during export
- "Show error message" option on the "Debug" tab renamed to "Show all error messages" and is now disabled by default
- "fixed" an issue with getting stuck during the "Building tree structure" step
- fixed a bug with listSearch that could make it not work in some conditions
- fixed a rare bug for resource files with the same name, that caused their data to be overwritten and become incorrect

AssetStudioGUI/Components/TreeViewExtensions.cs

@@ -40,7 +40,7 @@ namespace AssetStudioGUI
                 hItem = node.Handle,
                 mask = TVIF_STATE,
                 stateMask = TVIS_STATEIMAGEMASK,
-                state = 0
+                state = TVIS_STATEIMAGEMASK  //temp bugfix for an issue with getting stuck during the "Building tree structure" step
             };
             SendMessage(node.TreeView.Handle, TVM_SETITEM, IntPtr.Zero, ref tvi);
         }