Upgrade module dependencies

[neilcook]

• This involved also fixing several slices.SortFunc functions, because the sort function now returns int not bool

[Luit]

I'd say drop the x/exp dependency and use the standard lib slices. From what I can see that's the same as the new x/exp/slices (SortFunc with int return).

edit: all funcs in x/exp/slices/sort.go just call standard library functions in that version

[neilcook]

I'd say drop the x/exp dependency and use the standard lib slices. From what I can see that's the same as the new x/exp/slices (SortFunc with int return).

edit: all funcs in x/exp/slices/sort.go just call standard library functions in that version

Yes good idea