run some benchmarks

[matcool]

would be fun i think

[matcool]

not a benchmark but a compliance test suite

[matcool]

did some small benchmarks

[matcool]

v3.1.5, speed is about equal with nlohmann (though still slower on avg), except for when parsing via an std::istream :(

(edit: dump accidentally timed both parsing and dumping, instead of only dumping. matjson and nlohmann are equal in terms of dumping)

[matcool]

3.2.0, times vary a lot but file parsing is much faster!
nlohmann tests switched to ordered_json, to make it fair with matjson