Triple quote multiline string macros not working.

[Ismael-VC]

Reference: https://gitter.im/JunoLab/Juno?at=56990809a03e28ad1adee624

[MikeInnes]

It might be good to make a special case in the heuristics here, as it comes up a fair bit for docstrings etc

[pfitzseb]

Might actually be worthwhile to switch to a Tokenize/CSTParser based block detection system.