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/error/mod.rs

@@ -0,0 +1,20 @@
+//! Various errors the pipeline can produce
+mod import_all;
+mod no_targets;
+mod not_exported;
+mod not_found;
+mod parse_error_with_tokens;
+mod project_error;
+mod too_many_supers;
+mod unexpected_directory;
+mod visibility_mismatch;
+
+pub use import_all::ImportAll;
+pub use no_targets::NoTargets;
+pub use not_exported::NotExported;
+pub use not_found::NotFound;
+pub use parse_error_with_tokens::ParseErrorWithTokens;
+pub use project_error::{ErrorPosition, ProjectError, ProjectResult};
+pub use too_many_supers::TooManySupers;
+pub use unexpected_directory::UnexpectedDirectory;
+pub use visibility_mismatch::VisibilityMismatch;