Add initial version of value analysis and dataflow constant propagation

Author: jachris

src/lib.rs

@@ -471,7 +471,11 @@ pub trait Labeller<'a> {
 /// Escape tags in such a way that it is suitable for inclusion in a
 /// Graphviz HTML label.
 pub fn escape_html(s: &str) -> String {
-    s.replace('&', "&amp;").replace('\"', "&quot;").replace('<', "&lt;").replace('>', "&gt;")
+    s.replace('&', "&amp;")
+        .replace('\"', "&quot;")
+        .replace('<', "&lt;")
+        .replace('>', "&gt;")
+        .replace('\n', "<br align=\"left\"/>")
 }
 
 impl<'a> LabelText<'a> {