Undocumented predicates

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

 prepare_for_writing(Arg1, Arg2)

 finish_writing(Arg1)

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

 write_call_edge(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8)

 write_load_edge(Arg1, Arg2, Arg3, Arg4)

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

 write_predicates(Arg1, Arg2, Arg3)

 write_file_as_element(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7)

 write_file_as_element(Arg1, Arg2, Arg3, Arg4, Arg5, Arg6, Arg7, Arg8)