Added option to move all related files when renaming

This probably resolves https://trello.com/c/IzNiSitU/230-move-additional-files (at least until something better comes along)

It is quite simple: there is a new option ("AutoMoveRelatedFiles"), which when enabled, after moving the video file, also moves all files with the same filename and a different extension (i.e. all *.srt, *.nfo, *.jpg etc. files).