v1.0.2

Public release of GraphQL-core-next, based on GraphQL.js v14.1.1.

In addition to incorporating the latest changes from GraphQL.js,
this release also contains the following improvements and changes:

• Add traceback to GraphQLErrors (#23)
• Fix lexer issue with empty string (#18)
• Keep a list of middleware resolvers (#16)
• Support __typename attribute on data objects
• Restrict output via inspect() in error messages
• Remove contain_subset helper since it is not used any more