Undocumented predicates

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

 add_linear_11(Arg1, Arg2, Arg3, Arg4)

 add_linear_f1(Arg1, Arg2, Arg3, Arg4, Arg5)

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

 normalize_scalar(Arg1, Arg2)

 delete_factor(Arg1, Arg2, Arg3, Arg4)

 mult_linear_factor(Arg1, Arg2, Arg3, Arg4)

 nf_rhs_x(Arg1, Arg2, Arg3, Arg4, Arg5)

 isolate(Arg1, Arg2, Arg3, Arg4)

 nf_substitute(Arg1, Arg2, Arg3, Arg4, Arg5)

 mult_hom(Arg1, Arg2, Arg3, Arg4)

 nf_coeff_of(Arg1, Arg2, Arg3)

 renormalize(Arg1, Arg2, Arg3)