Graphql-complexity

This release fixes a bug with `__typename` fields, as they were considered complex nodes like any other field.
Now fields named `__typename` will be instantiated as `MetaFields` in Complexity Tree, and a complexity of `0` will be automatically assigned.

This release adds support for:
- Introspection queries are no longer computed by complexity algorithm
- List fields are taken into account in the complexity algorithm. Field complexity is multiplied by the size of the field, which should be given by argument (`first` by default).
- `include` and `skip` directives are also taken into account for complexity. If the field is ignored, its complexity is replaced by 0.

Releases contributed by Checho3388 via https://github.com/Checho3388/graphql-complexity/pull/7, https://github.com/Checho3388/graphql-complexity/pull/6, https://github.com/Checho3388/graphql-complexity/pull/5, and https://github.com/Checho3388/graphql-complexity/pull/1.

First release! A lot of things have been added, so there is nothing to say but "See the README.md" for more info.