This is relatively unoptimised right now, but should be efficient enough
for most practical applications.
- Add textutils.json_null. This will be serialized into a literal
`null`. When deserializing, and parse_null is true, this will be
returned instead of a nil.
- Add textutils.unserializeJSON (and textutils.unserializeJSON). This
is a standard compliant JSON parser (hopefully).
- Passing in nbt_style to textutils.unserializeJSON will handle
stringified NBT (no quotes around object keys, numeric suffices). We
don't currently support byte/long/int arrays - something to add in
a future commit.
