It would be helpful if the documentation for Point::getAngleToPoint specified the return range, i.e. (-pi, +pi]. The way it is currently phrased suggests [0, tau).
Currently I have to go to the definition, google 'std::atan2', realise that even cppreference gets it wrong (it is a half open interval), and then test it myself on ideone. Which only takes a minute, but still it would be nice to just hover over the method & see.