use move semantics

[schiller-manuel]

No description provided.

[chrfalch]

This is awesome, @schiller-manuel, thanks for going through all of this.

I have one question, however, and pardon my rusty C++ skills here - since parameters are mainly passed as const references - wouldn't this mean that there is no need for std::move in a lot of the places where they've been added in your PR?

Obviously there are some places where it is correct to use it - and we should definitely change those.

[schiller-manuel]

I only used std::move when not passed by const ref, at least that was the plan :) If you find instances where args are passed by const ref and I added std::move, let me know.

[chrfalch]

LGTM!