Undocumented predicates

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

 preprocess(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6)

 topsem(Arg1, Arg2)

 topatt(Arg1, Arg2)

 topstr(Arg1, Arg2)

 topcat(Arg1, Arg2)