Log Message:
graphics/oxipng: import package

Oxipng is a multithreaded lossless PNG compression optimizer. It can be used
via a command-line interface or as a library in other Rust programs.

It began as a complete rewrite of the OptiPNG project with the core goal of
implementing multithreading, which would be very difficult to do within the
existing C codebase of OptiPNG.