Types package

[davidebianchi]

Is your feature request related to a problem? Please describe

It is correct to have types in a specific package, or should them be in the package which uses them?

[fredmaggiowski]

the types package was meant to be useful to third parties integrating with rönd data models; also having them in a standalone package helped preventing cyclic dependencies, now that package definition has been reworked (and I think we found a good solution) we could move them in a specific package, thought.