Folded block scalars with whitespace at the end causes problems

While investigating #84 I realized that the yaml library parses weirdly when there is whitespace at the end of lines in a folded block scalar.

When `scan_folded_as_literal: false`, you get the original bug shown in issue #84.

When `scan_folded_as_literal: true`, you get the following with the same input:
```yaml
Foobar:
baz: "Lorem Ipsum is simply dummy text of the printing_and_typesetting industry.
\n#magic___^_^___line\n"
Foobaz:
baz: "foobar"
```

Will need to figure out why whitespace at the end of the line causes the library to think it's not printable.