jni-v0.14.0

What's Changed

• Added DynamicLibraryLoadError which is thrown when the dynamic library fails
  to load. HelperNotFoundError will only be thrown when the helper library
  cannot be found.
• Update the README.md to include info about generating bindings for built-in
  java types.
• Do not require a dylibDir when running Jni.spawn from Dart standalone,
  instead use the default value of build/jni_libs.
• Added JArray.of, which allows a JArray to be constructed from an
  Iterable.
• Added JObject.isA, which checks whether a JObject is a instance of a
  java class.
• Do not require JAWT when building for desktop.
• Added JByteArray.from, which allows a JByteArray to be constructed
  from an Iterable<int>.