These classes are now constructed with an interface adapter. This moves
complexity from various places into the interface adapter class, or to
some factories which now implement the different flavors of input.

Furthermore, input adapters are kept in std::shared_ptr to avoid the
need of manual deletion.

One test case for CBOR and MessagePack assumed little endianess.

We totally forgot to implement the comparison operators other than ==
and != for scalar types. Consequently, comparing a JSON value with a
scalar type led to compile errors.

Do not store eof() in a char buffer…

add enum class default conversions

TIL about C++:

executing m[key()]=val(); for a std::map executes

First key() then val() with Clang

First val() then key() with GCC

#wat

- removed uncached input stream adapter; it was too slow anyway
- implemented a class binary_read which parses CBOR based on input
adapters
- in the CBOR parser, numbers are created via memcpy to avoid undefined
behavior

Properly pop diagnostics

The implementation is non-standard. Deprecation allows a simpler API in
the future without removing any features.

NaN values never compare equal to themselves or to other NaN values.

https://blog.travis-ci.com/2017-03-28-xcode-83-ga-is-here