Most files suffered major changes

- Less ambiguous syntax
- Better parser (Chumsky only does tokenization now)
- Tidy(|ier) error handling
- Facade for simplified embedding
- External code grouped in (fairly) self-contained Systems
- Dynamic action dispatch
- Many STL additions

src/systems/io/mod.rs

@@ -0,0 +1,6 @@
+mod bindings;
+mod facade;
+mod flow;
+mod instances;
+
+pub use facade::{io_system, IOStream, IOSystem};