[macOS] Acquire non-ugly file type icons, fix file type icons

[TomHarte]

Background:

Clock Signal currently attempts to provide icons for the Finder, etc, for all associated file types. For whatever reason* those don't appear. Because they are somewhat incongruous with modern macOS norms — they're photographic — I haven't pursued this problem very vigorously.

Desired task:

Construct or obtain some icons that fit current norms, ensure that they appear appropriately in the Finder.

* quite possibly because they're provided as PNGs at a single resolution and despite the long-ago disappearance of Apple's icon conversion tool, and the fact that Xcode is apparently happy with that, possibly .icns files are the way to go?

[mbrethen]

Are you referring to the disk image icons displayed in the host system?

[mbrethen]

When specifying icons in macOS, you use an icon file (with extension .icns), which is capable of storing the icon at several different resolutions. I created the floppy525 apple icon image (.icns) as an example. I think Xcode Tools includes an Icon Composer app to create icon resource files. floppy525.zip