delete ROM files when deleting games in the UI

[dark]

I would like to see the application deleting the rom files when a game is removed.

As now, the game is removed from the UI but the file stay there. Any app nowadays allow to delete files from the UI (like Itunes, just to mention one). If there is concern about deleting roms, you can put a warning message with an OK to push, before deleting roms files.

[Brad Cheyne]

Duplicate of #101.