Changes Header, ReqBody and QueryParam to take a modifier list.
Resolves https://github.com/haskell-servant/servant/issues/856
ResponseHeader story turns to be somewhat ugly, but it can be made
elegant when https://github.com/haskell-servant/servant/issues/841 is
implemnted, then we can omit HList aka Header Heterogenous List
implementation.
- servant-server changes:
Writing server side intepretations is quite simple using
`unfoldRequestArgument`, which makes Header and QueryParam look quite
the same.
`ReqBody` cannot be easily made optional with current design (what that
would mean: No Content-Type Header?), so that dimensions isn't used
there.
- Add HasLink for all the rest ComprehensiveAPI combinators
- Add 'tricky' Header', QueryParam' endpoints to ComprehensiveAPI
- servant-docs: Quick'n'dirty implementation. Don't use modifiers information (yet).
We use NoContent to signify an empty response nowadays. This commit
replaces all occurences of () with NoContent so that all packages use
the new semantics.