Added generators test.
Added generators test.

- tests simple enumeration & explicit returns.

iolevel/peachpie,iolevel/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept,iolevel/peachpie-concept,peachpiecompiler/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept,iolevel/peachpie