Merge pull request #2988 from Montellese/xsp_extensions

smartplaylists: support for virtual folders

diff --cc language/English/strings.po
Simple merge

diff --cc xbmc/dialogs/GUIDialogSmartPlaylistRule.cpp
Simple merge

diff --cc xbmc/filesystem/SmartPlaylistDirectory.cpp
Simple merge

diff --cc xbmc/playlists/SmartPlayList.cpp
Simple merge

diff --cc xbmc/playlists/SmartPlayList.h
Simple merge

diff --cc xbmc/utils/DatabaseUtils.h
Simple merge