Move PVR options to separate group in management dialog

Also add shortcuts to launch last tv channel, last radio channel, last
channel
Library sources now show in video library group in management dialog
uPnP explorer tweaks

uPnP Source now appears below standard video/music library links
uPnP sources queried during loading of shortcuts, so the list of
sources will appear first time the user selects it (XBMC workaround)
Localize various management dialog labels
Indicate shortcut will invoke management dialog explorer

Available shortcuts that will invoke the management dialog explorer are
now appended with (>)