Support for 18x18 and 18x18@2x

[SamusAranX]

Apple's own ICNS files (namely a few of the Sidebar*.icns files in /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/) contain 18x18 and 18x18@2x images, but this library apparently doesn't support them.
I tried forking this repo and adding support myself, so I could submit a pull request, but sadly, I don't know enough C. Can you please add support for this?

Here's two screenshots of Preview.app's info panel, taken from SidebarMacProCylinder.icns:

[pabs3]

Is there a way to download copies of these images?

[SamusAranX]

Sorry for the late reply, I completely forgot about this. Here's one such file:
SidebarMacPro.icns.zip

[pabs3]

Thanks. I'm working on the upstream project from before this fork and more samples are always useful. This sample is really useful in particular, it contains almost entirely chunks that are unknown to libicns and several that are unknown to Wikipedia. I'm not sure when I'll get around to working on supporting this file, hopefully some time this year.