doughlang: "fix" semi elision, add "fully qualified" paths, add proper pattern prec parsing.

This actually gets some old code parsing!

src/main.rs

@@ -119,7 +119,7 @@ fn pats() -> Result<(), Box<dyn Error>> {
             return Ok(Response::Break);
         }
         loop {
-            match parser.parse::<Pat>(PPrec::Max) {
+            match parser.parse::<Pat>(PPrec::Min) {
                 Err(ParseError::FromLexer(LexError { res: "EOF", .. })) => {
                     break Ok(Response::Accept);
                 }