TO DO:
 - new implementation of debug messages:
   debug messages should be printed to .cdw.log file

 - full support for xorriso

 - remove unnecessary stuff from cdw_config_t, move it to cdw_task_t;
   create "cdw_task_t permanent_task" that stores parts of configuration;

 - corretcly handle situation when verifying a disc and an image file,
   and the image is larger than track on disc - cdio may throw an
   error while reading end of track, and cdw will interpret this as
   disc access error;

 - make sure that "eject tray after X" checkbox works properly

 - more signal handlers for signals causing exit;


 - make controlling of menus more consistent:
I'm noticing it's quite awkward to select files and try to decide whether to
use ESC or 'q' to quit.
The cdw menus and cdw application seem to be diverse as to which key it
requires to exit/quit and leave a menu.
Personally, I'm for specifying both.  Make it easy for the user!


DONE:

 - add "-root" option in mkisofs options

 - move .cdw.log, .cdw.conf and .cdw.colors to ~/.cdw/

 - add support for ~/.mkisofsrc (but only reading the file)