s/to to/to/

As <iostream> is not included in json.hpp any more, all code examples need to include <iostream> now.

Maybe the simple approach is working now - at least it is in https://github.com/taocpp/PEGTL/blob/master/.travis.yml

Removed deprecated documentation of the comparison operator.

The documentation mismatched the actual code.

To have nothrow-copy-constructible exceptions, we inherit from
std::runtime_error which can cope with arbitrary-length error messages.
Intermediate strings are built with static functions and then passed to
the actual constructor.

Ran “make pretty” and added a note to the README file.

I created a wiki page
https://github.com/nlohmann/json/wiki/Road-toward-3.0.0 to describe the
transition toward version 3.0.0. On this page, all API-breaking changes
shall be documented.

The library does not preserve the insertion order of object keys. There
are frequent requests to change the library in this aspect. The README
and the contribution guidelines now contain links to containers that
can be used to replace std::map to preserve the insertion order.