Support braceless root objects

[Talv]

Quoting RFC [1]

A Hjson text is either a serialized value or a root object.

Hjson-text = ws-c ( root-object / value ) ws-c

Also from "5. Objects" section:

If the Hjson text defines an object it does not have to include the braces at the root level: root-object = member *( value-separator member ) [value-separator]

See test case [2].

[1] https://hjson.github.io/rfc.html#hjson-grammar [2] https://github.com/hjson/hjson/blob/49abb794b1e0305e84261fd1bebe20e17dd4626e/testCases/extra/root_test.hjson