Contract factories and bytecode introspection (#305)

* Support for CREATE, CLONE and BYTECODE_HASH

* Add missing files

* Pushed the clone example through the typechecker

* CLONE compiles

* Fix dependent type in CLONE

* Bytecode hash fixes

* Refactor

* Refactor 2

* move some logic away

* Fixed some error messages. Type inference of child contract still does some random shit\n(mistakes arguments with result type)

* CREATE sometimes compiles and sometimes not

* Fix some scoping/constraint issues

* works, needs cleanup

* cleanup

* Fix some tests. Remove optimization of singleton tuples

* Fix default argument for clone

* Cleanup

* CHANGELOG

* Mention void type

* Address review, fix some dialyzer errors

* Please dialyzer

* Fix failing tests

* Write negative tests

* Docs

* TOC

* missing 'the'

* missing 'the'

* missing 'the'

* missing 'the'

* mention pre-fund

* format

* pre-fund clarification

* format

* Grammar in docs

test/contracts/clone.aes

@@ -0,0 +1,28 @@
+
+contract interface HigherOrderState =
+  entrypoint init : () => void
+  entrypoint apply : int => int
+  stateful entrypoint inc : int => unit
+
+contract interface LowerDisorderAnarchy =
+  entrypoint init : (int) => void
+
+
+main contract C =
+  // both `s` and `l` should be of type `HigherOrderState` in this test
+  stateful entrypoint run_clone(s : HigherOrderState, l : LowerDisorderAnarchy) : HigherOrderState =
+    let s1 = Chain.clone(ref=s)
+    let Some(s2) = Chain.clone(ref=s, protected=true)
+    let None = Chain.clone(ref=s, protected=true, gas=1)
+    let None = Chain.clone(ref=l, protected=true, 123) // since it should be HigherOrderState underneath
+    let s3 = Chain.clone(ref=s1)
+    require(s1.apply(2137) == 2137, "APPLY_S1_0")
+    require(s2.apply(2137) == 2137, "APPLY_S2_0")
+    require(s3.apply(2137) == 2137, "APPLY_S3_0")
+    s1.inc(1)
+    s2.inc(1)
+    s1.inc(1)
+    require(s1.apply(2137) == 2139, "APPLY_S1_2")
+    require(s2.apply(2137) == 2138, "APPLY_S2_1")
+    require(s3.apply(2137) == 2137, "APPLY_S3_0")
+    s1