v1.4.0

This release removes all metadata for the @urql/devtools extension from the core
urql package. This data will now be generated internally in the devtools exchange
itself. Please also upgrade to the latest @urql/devtools version if you're using
the extension.

This release has mainly been focused on minor refactors to keep the bundlesize low.
But it also introduces new features, like specifying a default requestPolicy and
a new polling option on useQuery!

This release also exports makeResult and makeErrorResult, which will reduce the
boilerplate code that you need for custom fetch exchanges.

• Minor bundlesize optimizations and remove debugExchange in production (see #375)
• ✨ Add requestPolicy option to Client to change the default request policy (see #376)
• ⚠ Remove dependency on graphql-tag and improve Operation.key hashing (see #383)
• Remove networkLatency and source metadata from context, and delete useDevtoolsContext (see #387 and #388)
• ✨ Add support for polling with pollInterval argument to useQuery, by @mxstbr (see #397)
• ⚠ Prevent __typename from being added to the toplevel GraphQL documents (see #399)
• Add operationName field to fetch request body (see #401)