Force breaks for nested records

[IwanKaramazow]

Fixes #1556 (partially)

/* before */
let person = {"name": {"first": "Bob", "last": "Zhmith"}, "age": 32};

/* after */
let person = {
  "name": {
    "first": "Bob",
    "last": "Zhmith"
  },
  "age": 32
};

Nested records/bs-obj sugar will always be printed with breaks.
Improves readability/extensibility of the code a lot.

Note that it only works with record or bs-obj sugar which contains another record/bs-obj/objects.
Force breaking for nested objects hasn't been implemented yet, because of some printing challenges.

[chenglou]

Thanks!