Enhance the builtin PLS playlists parser, which is quite strict and limited

Current PLS playlists parsing implementation explains it follows the format as described at:
http://en.wikipedia.org/wiki/PLS_(file_format)

However, this format is not really strict. For instance, even the example provided in that very same page won't be successfully parsed by current implementation:
http://en.wikipedia.org/wiki/PLS_(file_format)#Examples

Other software providing PLS playlists which QtMultimedia is not able to parse include totem-pl-parser, used in GNOME:
https://developer.gnome.org/totem-pl-parser/

Or VLC