Support associated types with bounds

It would be great if we can have associated types with bounds.
Current it reports the error:
```
error: The verifier does not yet support the following Rust feature: unsupported item
  --> reconciler/spec/mod.rs:34:1
   |
34 | / pub trait SomeTrait {
35 | |     type A: OtherTrait;
36 | |     type B;
37 | | }
   | |_^
```