nameref and gettitlestring

[mrpiggi]

It would be a nice feature for nameref to optionally use the expansion method of gettitlestring without setting the corresponding package option globally. This request is actually motivated by this discussion: https://github.com/latex3/latex2e/issues/307

As soon as there are some user-defined commands which should be ignored for generating \@currentlabelname one has to use the expansion method of gettitlestring. Setting \GetTitleStringSetup{expand=true} globally is maybe error prone, although I do not have a particular case in mind.

Maybe using protected expansion at least in headings by default or via option would be good as well. See also https://github.com/ho-tex/gettitlestring/issues/2 and https://github.com/ho-tex/gettitlestring/issues/3 The expansion is already protected.