Add some escape sequences as formatting characters

[frame-lang]

These might be useful to execute formatting instructions to the code generators. Once use case is when literal strings shouldn't just generate as an in place expression:

|e| 
   `a++` ^

This generates:

        if e._message == "e":a++            
            return

Which messes up Python. The idea is to use \n to (or maybe \n\t) to adjust:

|e| \n
   `a++` ^

See article.