Refacto/split basic json

Those macros are used to reduce template argument boilerplate

These versions are still not working properly: https://travis-ci.org/nlohmann/json/jobs/251675281

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

Don't include <iostream>, use std::make_shared

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

avoid bloat caused by <iostream> and std::cout and friends in apps where
iostream are not used.

There was an issue in the documentation example before. Unfortunately, I did not recreate the example outputs.

It makes no sense to have this special exception. Instead of throwing when an input adapter is created, it is better to detect a parse error in later usage when an EOF is "read" unexpectedly.

Also added some comments and improved the documentation.

These breaks were just added to silence a GCC warning - the GCC is right about warning as it cannot know that the expect function will not return in these two scenarios.

It seems these functions are not required any more. The code was added in commit 7e324578 to fix issue #171. There are still regression tests for #171, so when this commit passes the CI, the functions may be removed for good.

See https://twitter.com/travisci/status/880550780368855040

I have no idea why this test has been removed in the first place.

When an empty vector was passed to the parse function, an empty iterator range was used to construct an input iterator. Unfortunately, we then cannot use the start iterator to derive a pointer from.

Found with Xcode's undefined behavior sanitizer.

Removed deprecated documentation of the comparison operator.

fix typo in operator__notequal example

Fix MSVC warning C4819

Travis aborts tests if they do not produce output for 10 minutes. This commit shall fix this.