Collect "most recently used" statistics for autocompletion

Currently QtCreator offers auto-completion suggestions sorted in alphabetical order. Usually it works really bad:

For example for "std::st"  it suggests "static_pointer_cast, stod, stof..."  instead of commonly used std::string.  Same problem with other standard library classes.

I've noticed that some other IDEs are much smarter in this area (looks like some have some predefined priority order for standard library. ).