WASM contracts MVP (#5679)

* lifetime issues

* refactor to new 'native env'

* descriptors and such

* wasm mvp continued

* finalized env/ext bindings

* descriptor -> call_args

* inject gas counter

* result processing and engine activation

* tabify some source files

* needs return new

* wasm tests initial

* erradicate warnings

* origin in the descriptor

* update test repo

* payload verification tests

* identity return payload test

* some test description

* dispersion test

* check length here

* suicidal contract

* engine params

* fix typo

* review fixes

* submodule update

* update - purge reserved space

* doc effort

* more review fixes

* fix error message

* fix dependency url

* reorg error handling

* update submodule

* update utils

* update to latest parity-wasm

* tabify

* fix wasm magic header

* update dependencies

* external create and tests

* update to latest tests

* extra trace info

* Update parity-wasm

* update wasm-utils also

* few traces and result handle change

* alter trace content

* fix issues with optimizer, update to latest parity with validator, etc

* static initialization

* license preamble

* update wasm crates and gas costs

* fix grumbles

* bring back lifetime

* fix compilation

ethcore/src/engines/mod.rs

@@ -376,6 +376,11 @@ pub trait Engine : Sync + Send {
 		self.snapshot_components().is_some()
 	}
 
+	/// If this engine supports wasm contracts.
+	fn supports_wasm(&self) -> bool {
+		self.params().wasm
+	}
+
 	/// Returns new contract address generation scheme at given block number.
 	fn create_address_scheme(&self, number: BlockNumber) -> CreateContractAddress {
 		if number >= self.params().eip86_transition {