changed: Refactor CGUIMediaWindow::ShowShareErrorMessage() so it works with any path
fixed: Properly fallback to root in case getdirectory fails in Update() + show error dialog (in line with a54cb0d795e6c519c0f62429b23ece0f1c22f4ba)
Merge pull request #1997 from arnova/fm_fixes_for_guimediawindow_too

Filemanager fixes for guimediawindow too