* keygen.c (start_tree): New function to "prime" a KBNODE list.
(do_generate_keypair): Use it here rather than creating and deleting a
comment packet.
* keygen.c (gen_elg, gen_dsa): Do not put public factors in secret key as
a comment.
* options.h, encode.c (encode_simple, encode_crypt), keygen.c (do_create):
Remove disabled comment packet code.