Fix lister assert when re-selecting file.

SWUpdateGUI crashes, when:
1. selection is made in file-selection-window;
2. window is closed using "Cancel" button;
3. file-selection window is opened again;
4. the same file is selected.

The crash is due to assertion fail in lister widget's onSelectLine handler.
Whenever file list widget is repopulated, the selection state is not cleared,
which causes assert to fail.

This fix changes the way file list is repopulated to clear selection state and avoid
error.

Signed-off-by: Andrzej Szczepański <[email protected]>

SWUpdateGUI.lua

@@ -608,7 +608,7 @@ function FileboxWindow:scanmedia()
   end
   self.filelist = files
   local list = self:getById("files-list")
-  list:clear()
+  list:setList(List:new())
   for i=1,#files do
       local entry = {}
       table.insert(entry, GetFileName(files[i]))