Collator for the "adder" (formerly basic-add) parachain and various small fixes (#438)

* update basic_add wasm

* wasm feature and collator feature

* move test parachains around a little

* fix wasm build for basic_add

* move basic_add to adder, introduce README

* minimal basic_add collator

* ensure collator messages are sent in the right order

* more logging

* route consensus statements to all peers

* minor bugfixes for parachains

* genesis builder accounts for parachain heads

* fix parachains tests

* targets for txpool

* tweak runtime + collator

* fix version in adder-collator

* consistency for overflowing

* adjust comment

* fix stable test run

* remove dummy registration test

* final grumbles

polkadot/test-parachains/build.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -e
+
+# Make LLD produce a binary that imports memory from the outside environment.
+export RUSTFLAGS="-C link-arg=--import-memory -C lto=fat -C panic=abort"
+
+for i in adder
+do
+	cd $i/wasm
+	cargo +nightly build --target=wasm32-unknown-unknown --release --no-default-features --target-dir target
+	wasm-gc target/wasm32-unknown-unknown/release/$i'_'wasm.wasm target/wasm32-unknown-unknown/release/$i.wasm
+	cp target/wasm32-unknown-unknown/release/$i.wasm ../../../parachain/tests/res/
+	rm -rf target
+	cd ../..
+done