Create output dir + recursively conversion abilities

[cristianpark]

First of all, hands down to a great tool in Linux, I was struggling a bit converting files to CHD format and the tool manages that magically. Kudos to the devs!

I'm just starting using it converting bin/cue files for PSX and I have a structre like

games_folder
- game2.bin
- game2.cue
- game3.bin
- game3.cue
- game1_folder
-- game1.cue
--game2.bin

within the root folder and the tool only converts game2 and game3 in the example structure.

Another little nuance is that the output folder specified with -d doesn't get created by default and most of the time you just want the folder as a temporary placeholder to verify the converted files so it doesn't exist before executing the command.

Thanks once again for such good tool!