Feat: lots of improvements

tests/forth/sound.rs

@@ -94,7 +94,7 @@ fn param_only_emit() {
     assert!(outputs[0].contains("voice/0"));
     assert!(outputs[0].contains("freq/880"));
     assert!(!outputs[0].contains("sound/"));
-    assert!(!outputs[0].contains("dur/"));
+    assert!(outputs[0].contains("dur/"));
     assert!(!outputs[0].contains("delaytime/"));
 }
 
@@ -138,3 +138,9 @@ fn polyphonic_with_at() {
     let outputs = expect_outputs(r#"0 0.5 at 60 64 note sine s ."#, 4);
     assert_eq!(outputs.len(), 4);
 }
+
+#[test]
+fn explicit_dur_zero_is_infinite() {
+    let outputs = expect_outputs("880 freq 0 dur .", 1);
+    assert!(outputs[0].contains("dur/0"));
+}