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/stl/bool.orc

@@ -0,0 +1,6 @@
+export const not := \bool. if bool then false else true
+export macro ...$a != ...$b =0x3p36=> (not (...$a == ...$b))
+export macro ...$a == ...$b =0x3p36=> (equals (...$a) (...$b))
+export macro if ...$cond then ...$true else ...$false:1 =0x1p84=> (
+  ifthenelse (...$cond) (...$true) (...$false)
+)