rest-example client: Regenerate with new haskell-src-exts
Reproduction of incorrect error conversion, accept header is text/json but fromXML is called
rest-gen: Fix bug where end points with no output or error dictionaries would set the accept header to text/json but call fromXML on the error response
Merge pull request #82 from silkapp/void-error-conversion

rest-gen Haskell: Fix default error conversion when there is no output or error dictionaries.
rest-gen: Bump to 0.16.1.1
rest-example: remove redundant parentheses.
rest-types: sort exposed modules.
Indicate empty dictionary list in types.

The type of the dictionary is now a type-level Maybe, with Nothing
indicating an empty list of dictionaries. This allows us to choose,
based on the context, if we want to treat the empty list as
polymorphic, or as monomorphic (e.g. ()). This means we no longer need
to `some*` combinators: we can just allow an empty dictionary to be
added to. However, in the driver code we treat empty dictionaries as
(), as before.

Fixes #31.
Use Void instead of () for 'no errors'.

This is better, since previously it was possible to throw (), which
wasn't the intention. Occasionally this required the use of `error`, for
example when mapping over a Reason_ to extend it to some (Reason e).

The only remaining wart is that the XmlPickler instance requires an
unpickler, but there's not much to be done about that.

Fixes #70.