Add option to font renamer to allow overwriting files.

[SolidTux]

This exposes the overwrite option of makeOutputFilename as a command line flag.

[ftCLI]

There's the risk, especially when processing a large number of files, that some of them could be deleted without warning. I see that in your PR the default value is False, and that's ok. Could you just add a warning in the help string so to make clear to the users that they coul loose files with that option active?

[SolidTux]

That makes sense. Maybe like this?

[ftCLI]

That makes sense. Maybe like this?

Yep. Thanks!

[SolidTux]

Thank you for the yet again superfast and helpful response!