Explicitly test inner types iff they should be re-exported?

[tcharding]

In doing #315 we discovered that its easy to forget to re-export inner types or re-export the wrong one. 'inner' means the type used by lists and maps. For an example see d561e5c

However this highlights the fact that we are non-uniform in re-exporting 'auxillary' types and all the version specific sub-modules are private so if there is no re-export then the type is unavailable.

E.g v17::GetPeerInfo wraps a vector of PeerInfo types. We re-export it. However there are a myriad of other types that we do not re-export.

I'm not sure if we should or not?

[jamillambert]

Duplicate of #137

[tcharding]

Woops, thanks.