mpd: fix memory leak added by 67550d460
bindings: allow for binding multiple chains to one key
window: fix exiting from getString if helper indicates so
actions: add missing flag restriction for physical deletion
statusbar: use boost::format instead of c-style printf
actions: make askYesNoQuestion use boost::format
update copyright message
remove remnants of --now-playing command option
tag editor: fix filename change detection
uniformize ways to convert strings into screen type