Avoiding manual conversion step & autocompletion

[mhuisi]

When I have time to work on this again (in ~2 months), I'd like to adjust the API so that no extra conversion step is necessary at the end and work on autocompletion.

For the former, a macro approach could work well, where a type-safe output structure is generated either from a Parsed value or even directly at the start using the configuration macro. The library does not really track the real type right now, so the latter should be safer.