Spice21 Internal Crate

A very simple crate, broken out solely for sake of rustc's requirement that proc-macro crates only export their procedural macros. (These function as something like compiler plug-ins.)

This crate exposes the internals that spiceproc (the procedural-macros crate) depends on. It is not designed to be particularly useful outside of Spice21. All pub annotations should be read as "public for Spice21".