Speed up /undline similarly

Speed up /undline similarly
- Change find_exact_conf_by_address() to work for dlines also.
- Use find_exact_conf_by_address() to find the dline and
  abort immediately if there is no such dline.
- When removing a permanent dline, remove the dline from
  the data structures instead of rehashing bans.
- Convert alternative ways to write the same dline to the
  one in the found dline. (This was changed in unkline too.)