- add support for unknown delegate construction pattern. The method is compiler-generated, but has no compiler-generated name, we should be able to infer lambda usage from anonymous types used in the signature (i. e., the method can only be used as lambda, because that's where type names are optional).
- Add CombineExitsTransform in DelegateConstruction: this allows combining lambdas with multiple return statements into a single expression (as it is expected by query expressions).