Add xtd framework to GUI section

The original project has been retired and is only as a read only git
repo available.

Development of djinni happens nowadays via https://github.com/cross-language-cpp

The submitted link points to the documentation site.

Introduced CXXGraph header-only library, that provides utilities for representation and algorithms on graph.

fmtlog is a performant asynchronous logging library using fmt library format. It's easy to use and might be the fastest C++ logging lib so far.

Previous link was pointing to a code.google.com repository, which
reported a 404 error.

New link seems to be not official, but working ;)

yaml-cpp is already listed on libhunt, adding it to the Yaml category here