Use prefixed keys for trie node. (#2130)

* Account for pending insertions when pruning

* Prefixed trie storage

* Comments

* Prefixed trie storage

* Fixed tests

* Fixed tests

* Bumped runtime version

* Bumped runtime version again

substrate/node/executor/Cargo.toml

@@ -6,7 +6,7 @@ description = "Substrate node implementation in Rust."
 edition = "2018"
 
 [dependencies]
-trie-root = "0.11"
+trie-root = "0.12"
 parity-codec = "3.2"
 runtime_io = { package = "sr-io", path = "../../core/sr-io" }
 state_machine = { package = "substrate-state-machine", path = "../../core/state-machine" }