[ocaml][messages] use quotes for char arrays

- char[] are now treated as 'real' strings
- no more delimiters for other arrays (where space characters should not
  appear)
[ocaml] backward compatibility on old array's delimiters
[python] update messages tool to deal with whitespaces in arrays
Merge pull request #942 from paparazzi/ivy_arrays

Remove array delimiters on Ivy messages