Allow setting the name of the leading directory

[pchan37]

Hello,

Right now, leading-dir is either true or false and if it's true, it uses the archive name as the name of the folder. It would be nice to allow the customization of the name of the directory. My primary use case for this is to create an App.app/Contents directory as root for a MacOS app.

Thank you.

[taiki-e]

This sounds reasonable. I would accept a PR to implement this.

[pchan37]

Ok, would we want to maintain backward compatibility and add a new variable such as leading-dir-path to hold the actual path and keep leading-dir as true/false? The default for leading-dir-path can be archive. Downside is leading-dir and bin-leading-dir would have different types.