The rule worked for values like:
flow-map: {a: foo, b: "bar"}
block-map:
a: foo
b: "bar"
But not for:
flow-seq: [foo, "bar"]
block-seq:
- foo
- "bar"
Also add tests to make sure there will be no regression.
Fixes: #208.
Original implementation was completely broken. Documentation and actual
behavior were different. Numbers and booleans were detected as wrong, as
well as explicit types.
Fixes#136 and #130.
