Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 infer_alias(Arg1, Arg2, Arg3)

 fastest_alias(Arg1, Arg2)

 library_alias(Arg1, Arg2)

 smallest_alias(Arg1, Arg2)

 current_alias(Arg1, Arg2)

 pretty_path(Arg1, Arg2)