* Remove unnecessary self-dependency
* Regenerate core/default.nix and build -core via callCabal2nix
* grpc-haskell-core: -Wall -Werror and fix warnings
* grpc-haskell: -Wall -Werror and fix warnings
* Update documentation
* Remove LD_LIBRARY_PATH sets from usesGRPC
...as they no longer seem to be needed.
* Remove dead code
* Remove core/default.nix
...as suggested by @evanrelf.
* echo client/server example: dead code removal, add command line params, improve output messages
* Add nix-build result to .gitignore
* Merge echo-client and echo-server directories to echo-hs/ directory; rename main modules accordingly
* Use our protobuf compiler to generate bindings for the Echo service
* Simplify echo.proto to just one endpoint; use highlevel client/server interfaces and codegen for echo example
* Remove repetition counts and thread spawns from echo client, parameterize payload
* Update default.nix
