Verify the storage root and tx trie root in runtime

Also refactor wasm exports to be stricter on invalid mem references.

Arkadiy Paronyan authored Jan 30, 2018 and asynchronous rob committed Jan 30, 2018

* Networking crate draft

* Started work on syncing algo

* Fixed query range

* BlockCollection tests

* In-mem client backend

* Fixed tests

* Renamed Transaction

* Removed stray println

* Docs

Also refactor `TestExternalities` into a single place.

Native executor