WIP. Currently only exposes a box2d.c struct for including and using box2d. I still got to try making something with it.

Running zig build compiles box2d to a static library. It is also available as a zig module. Check the sample/build.zig and main.zig for example usage.

Box2D requires an additional dependency to run tests. This is lazily loaded and it's tests aren't exposed through zig build test unless -Dbox2d_tests is specified.

• expose the C api.
• run the box2d unit tests.
• zig wrapper for c api.
• make something with this.
• try to get rid of libc?