Make sure that Postponed Evaluation of Annotations (PEP 563) works with parser #2
Description
Recently accepted PEP 563 paved the way for a more convenient way of creating self-referential annotations; it will be achieved by storing annotations as strings, so those will be only evaluated by type-checkers and other systems making actual use of those.
The declarative_parser should detect the use of postponed evaluation (enabled by future import in 3.7, default since 4.0) and evaluate the objects for type deduction for purposes of automated parser creation with FunctionParser and ClassParser.