Playlist files support refactoring, splitting File__ReferenceFilesHelper in different classes, update

git-svn-id: svn://svn.code.sf.net/p/mediainfo/code/MediaInfoLib/trunk@6594 45c5ae6f-87cc-4fd0-92ee-e4f023fd80da
Playlist files support refactoring, splitting File__ReferenceFilesHelper in different classes, update

git-svn-id: svn://svn.code.sf.net/p/mediainfo/code/MediaInfoLib/trunk@6595 45c5ae6f-87cc-4fd0-92ee-e4f023fd80da