v2.9.0

What's Changed

• Fix C implementation of script_safe escaping to not confuse some other 3 wide characters with \u2028 and \u2029.
  e.g. JSON.generate(["倩", "瀨"], script_safe: true) would generate the wrong JSON.
• JSON.dump(object, some_io) now write into the IO in chunks while previously it would buffer the entire JSON before writing.
• JSON::GeneratorError now has a #invalid_object attribute, making it easier to understand why an object tree cannot be serialized.
• Numerous improvements to the JRuby extension.

Full Changelog: v2.8.2...v2.9.0