(piqi) Improved handling of enums by "piqi to-proto"
(piqi) Improved handling of enums by "piqi to-proto"

- don't generate aliases for enums
- treat enum as a primitive type when used as a function parameter
- properly handle enum definitions embedded in function parameters

alavrik/piqi,Motiejus/piqi-deb,alavrik/piqi,Motiejus/piqi-deb,Motiejus/piqi-deb,alavrik/piqi,Motiejus/piqi-deb