Apollo fragment-based store observing

[alloy]

TODO:

• [x] Add pagination to example app
• [x] Pagination fragment requires @refetchable directive, is this normally enforced in the compiler or at runtime?
• [x] Introduce better way for ts import transform to know name of query artefact to import
• [x] Split hooks into files
• [x] Compiler needs to extract default variable values and use it in the fragments context
• [ ] Apollo Client watchQuery seems to always yield twice when data updates
• [x] Import refetch/pagination/subscription docs
• [ ] Consider switching from node root field to a private reserved field as to not cause any conflicts when reading cached node data etc. E.g. __node ?
• [ ] Consider merging the relay-compiler-language-graphitation package into the apollo-react-relay-duct-tape package, seeing as most-all of it is in service of that package
• [ ] Workout strategy for dev vs prod builds, specifically around stripping out invariant calls
• [ ] Write document on all this:
  • Why?
  • How does the architecture work?
    • The Global Object Identification spec
    • The compiler basics
    • The Node transform
    • The compiler output
    • The hooks and execution vs watch queries
    • The node cache field policy
  • How to use it?