 ? handle error when overwriting a file
 
 * give time estimates for progress bar
 * HIG compliant interface
 * progress dialog
 * autotools, l12n
 * handle exceptions even when they happen in callbacks
 * add support for GNOME encoding profiles

 * bug: the program's options aren't printed with --help

 -ok- bug: the dialog can only be showed once
 -ok- use a raw quality setting
 -ok- display aprox. bitrate
 -ok- choose dir, add recursively input files that need to be converted
