Merge 'origin/master' into ser-contract-ioc

# Conflicts:
#	demo/runtime/wasm/target/wasm32-unknown-unknown/release/demo_runtime.compact.wasm
#	demo/runtime/wasm/target/wasm32-unknown-unknown/release/demo_runtime.wasm
#	polkadot/runtime/wasm/target/wasm32-unknown-unknown/release/polkadot_runtime.compact.wasm
#	polkadot/runtime/wasm/target/wasm32-unknown-unknown/release/polkadot_runtime.wasm
#	substrate/executor/wasm/target/wasm32-unknown-unknown/release/runtime_test.compact.wasm
#	substrate/executor/wasm/target/wasm32-unknown-unknown/release/runtime_test.wasm
#	substrate/test-runtime/wasm/target/wasm32-unknown-unknown/release/substrate_test_runtime.compact.wasm
#	substrate/test-runtime/wasm/target/wasm32-unknown-unknown/release/substrate_test_runtime.wasm