Use std::move or inline expressions into place if used only once

Using the framework for counting usages and dependencies, we can determine if a particular value is used only once or what the last usage of that value is. If it's used only once and all of its dependencies are still the same where it's used, we can inline it, saving some copy operations. If we can determine the last place where the value is used, we can std::move it there, as usually move assignment is cheaper than copy assignment.