encode all literal-character types as ascii code for compatiblity with c symbol names

src/main.rs

@@ -95,11 +95,7 @@ struct LdmcPrimCMorphism {
 fn encode_type_to_symbol(dict: &mut impl TypeDict, t: &laddertypes::TypeTerm)-> String {
     match t {
         laddertypes::TypeTerm::Char(c) => {
-            match *c {
-                '\0' => { "NULL".into() },
-                '\t' => { "TAB".into() },
-                c => { format!("{}", c) }
-            }
+            format!("{}", (*c as u64))
         },
         t => dict.unparse(t)
     }