Allow calling a different instance of the current contract (#379)

Add functions as fields before inferring

Unbound untyped fields before binding typed ones

Fix failing tests

Make complex_types contract non-compatible with aevm

Reduce code duplication

Undo changes to test.aes

Remove special handling of __constructor__ field

Resolve field constraint by arity of contract function

Update CHANGELOG

Update CHANGELOG.md

Co-authored-by: Radosław Rowicki <35342116+radrow@users.noreply.github.com>

Split bind_field function

Add a comment about rebinding

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
 - Options to enable/disable certain optimizations.
+- The ability to call a different instance of the current contract
+  ```
+  contract Main =
+    entrypoint spend(x : int) : int = x
+    entrypoint f(c : Main) : int = c.spend(10)
+  ```
 ### Changed
 ### Removed
 ### Fixed