First try at multiline dict literals

As mentioned in #4145 this is a quick'n dirty attempt in letting the julia frontend parse '\n' or ';' separated dict literals.
It allows mixed comma/newline separated dicts but not arrays to stay coherent with the old behavior (which is this way to prevent matrix/array confusion if I had to guess).

All tests passes except some linalg tests that I can't try on my machine due to a faulty lapack install.
The code is not the cleanest but is the less intrusive I could do to try and not mess the existing parsing behavior.

Please, feel free to comment as it's my first time fiddling with flisp/the frontend.