Make fetchMore pass new variables to merge functions.
Make fetchMore pass new variables to merge functions.

This commit also deprecates the updateQuery function, while preserving its
existing behavior for backwards compatibility. If you're using a field
policy, you shouldn't need an updateQuery function.

Fixes #5951.

apollostack/apollo-client,apollostack/apollo-client,apollographql/apollo-client,apollographql/apollo-client,apollostack/apollo-client