This starts to establish the structure for an in-place rewrite of WINGs. An
actual redesign of WINGs may follow, but for now there are no plans to alter the
structure of WINGs substantially.
Having wings-rs depend on WINGs/WINGs/WINGsP.h was not working very well if all
of WINGs/ had to be built before wings-rs/. Moving wings-rs/ into WINGs/
addresses this.
We will use these to port W_Font, W_Screen, etc., to Rust.
Bindings are regenerated whenever the relevant C source files change and then
patched to make sure they will build. This is a bit hacky but will serve our
purposes: the struct definitions should be migrated to Rust sooner rather than
later, so the hackishness should be transient.
