🐛 Minor fixes

1.3.1

🐛 Fix getChildren

✨ Add schema declaration parser

Merge pull request #1 from hansott/feature-schema-parser

✨  Add schema declaration parser

✨ Add location property for each node

Merge branch 'master' of github.com:hansott/graphql-language

* 'master' of github.com:hansott/graphql-language:
  Update CONTRIBUTING.md

✨ Add VisitorBase and VisitorMany

• VisitorBase can be used to add a visitor without the need to implement every method of the visitor.
• VisitorMany can be used to add multiple visitors to the traverser.

🎉 Initial release

This is the initial release! Hooray.