Complete new implementation of xdg-user-dirs based on recent discussion at #kde-devel.
Qt 4.4 implements partially the xdg spec except for XDG_DOWNLOAD_PATH ( TEMPLATES and PUBLICSHARED is not required ), which is done using part of the previous code.

The reason to move for Qt code comes because portability to other platforms.
KDE have Autostart path, so the same old code was kept and behavior remains the same.