[PNG] cICP inserting tool released

Hello everyone,

Chris Seeger asked for a tool to insert CICP data into a PNG.
Good idea. So I spent this week writing one.
I just released it here:
https://github.com/ProgramMax/cicp_inserter/releases/tag/v1.0

Right now, it is only built and tested on Windows.
I'm going to add MacOS and Linux support next.

Feel free to file issues if you have feature requests.

Thanks!
-Chris B