Minimal parachain framework part 1 (#113)

* dynamic inclusion threshold calculator

* collators interface

* collation helpers

* initial proposal-creation future

* create proposer when asked to propose

* remove local_availability duty

* statement table tracks includable parachain count

* beginnings of timing future

* finish proposal logic

* remove stray println

* extract shared table to separate module

* change ordering

* includability tracking

* fix doc

* initial changes to parachains module

* initialise dummy block before API calls

* give polkadot control over round proposer based on random seed

* propose only after enough candidates

* flesh out parachains module a bit more

* set_heads

* actually introduce set_heads to runtime

* update block_builder to accept parachains

* split block validity errors from real errors in evaluation

* update WASM runtimes

* polkadot-api methods for parachains additions

* delay evaluation until candidates are ready

* comments

* fix dynamic inclusion with zero initial

* test for includability tracker

* wasm validation of parachain candidates

* move primitives to primitives crate

* remove runtime-std dependency from codec

* adjust doc

* polkadot-parachain-primitives

* kill legacy polkadot-validator crate

* basic-add test chain

* test for basic_add parachain

* move to test-chains dir

* use wasm-build

* new wasm directory layout

* reorganize a bit more

* Fix for rh-minimal-parachain (#141)

* Remove extern "C"

We already encountered such behavior (bug?) in pwasm-std, I believe.

* Fix `panic_fmt` signature by adding `_col`

Wrong `panic_fmt` signature can inhibit some optimizations in LTO mode.

* Add linker flags and use wasm-gc in build script

Pass --import-memory to LLD to emit wasm binary with imported memory.

Also use wasm-gc instead of wasm-build.

* Fix effective_max.

I'm not sure why it was the way it was actually.

* Recompile wasm.

* Fix indent

* more basic_add tests

* validate parachain WASM

* produce statements on receiving statements

* tests for reactive statement production

* fix build

* add OOM lang item to runtime-io

* use dynamic_inclusion when evaluating as well

* fix update_includable_count

* remove dead code

* grumbles

* actually defer round_proposer logic

* update wasm

* address a few more grumbles

* grumbles

* update WASM checkins

* remove dependency on tokio-timer

substrate/Cargo.lock

@@ -1234,7 +1234,6 @@ name = "polkadot-api"
 version = "0.1.0"
 dependencies = [
  "error-chain 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-executor 0.1.0",
  "polkadot-primitives 0.1.0",
  "polkadot-runtime 0.1.0",
@@ -1291,7 +1290,9 @@ name = "polkadot-collator"
 version = "0.1.0"
 dependencies = [
  "futures 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "polkadot-parachain 0.1.0",
  "polkadot-primitives 0.1.0",
+ "substrate-codec 0.1.0",
  "substrate-primitives 0.1.0",
 ]
 
@@ -1307,6 +1308,7 @@ dependencies = [
  "parking_lot 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-api 0.1.0",
  "polkadot-collator 0.1.0",
+ "polkadot-parachain 0.1.0",
  "polkadot-primitives 0.1.0",
  "polkadot-runtime 0.1.0",
  "polkadot-statement-table 0.1.0",
@@ -1355,6 +1357,16 @@ dependencies = [
  "tempdir 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "polkadot-parachain"
+version = "0.1.0"
+dependencies = [
+ "error-chain 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "substrate-codec 0.1.0",
+ "tiny-keccak 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasmi 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "polkadot-primitives"
 version = "0.1.0"
@@ -1454,17 +1466,6 @@ dependencies = [
  "transaction-pool 1.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "polkadot-validator"
-version = "0.1.0"
-dependencies = [
- "error-chain 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "polkadot-primitives 0.1.0",
- "serde 1.0.27 (registry+https://github.com/rust-lang/crates.io-index)",
- "substrate-primitives 0.1.0",
- "substrate-serializer 0.1.0",
-]
-
 [[package]]
 name = "pretty_assertions"
 version = "0.4.1"
@@ -1933,9 +1934,6 @@ dependencies = [
 [[package]]
 name = "substrate-codec"
 version = "0.1.0"
-dependencies = [
- "substrate-runtime-std 0.1.0",
-]
 
 [[package]]
 name = "substrate-executor"