Sample "include-what-you-use" results

This shows example output of the "include-what-you-use" tool on the wesnoth project.

The tool removes unnecessary headers, and ensures that each file actually includes / forward declares what it needs.

I stopped it after it ran through most of the "a" files, so about 70 files.
After I had to fixup some things in AI, I made a 3 line script that does this, after the iwyu tool runs.