Option to reduce margins (make icon larger)

[imaverage]

reduce margins (effectively make the injected icon bigger) so that the injected icon is more prominent when viewing in smaller sizes (like alfred preview thumbnail).

black is original injected size. if we could control this sizing, that would be great.

thanks!

[lgarron]

The goal of the project is to match the macOS native folder icons as closely as possible, but I wouldn't be opposed to an option for this. I'd be glad to review a PR that does the following:

• Figure out the maximum size that can be scaled and used all the way down to 16x16.
• Add an --embossing-size flag with the values match-native (default) and maximum.