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.
This introduces a clear separation between test data and test
binaries. Test data is moved into test/data, and the test binaries
move into test/src. A new CMake script specific to building the
tests is introduced in /test to slightly clean up the toplevel
one.
As well as tidying things up, this makes the next step trivial...
