* Fix Oscaris problems with the trustdb.

    * add test cases for invalid data (scrambled armor or other random data)

    * fix the expire stuff for v4 packets.

    * check whether it is valid to pack the signature stuff (onepass, data,
      sig) into a compressed packet - or should we only compress the data?
      what does pgp 5 do, what does OpenPGP say=

    * invalid packets (Marco)

    * add some sanity checks to read_keyblock, so that we are sure that
    the minimal requirements are met (?)

    * what about the CR,LF in cleartext singatures?

    * make preferences work

    * rewrite --list-packets or put it into another tool.

    * add usage arguments to get_key_byname or return a PKC_LIST with
      all keys and add a selection.

    * Burn the buffers used by fopen(), or use read(2). Does this
      really make sense?

    * enable a SIGSEGV handler while using zlib functions

    * Change the buffering to a mbuf like scheme? Need it for PSST anyway.
    * add checking of armor trailers
    * remove all "Fixmes"

    * Change the internal represention of keyid into a struct which
      can also hold the localid and extend the localid to hold information
      of the subkey number because two subkeys may have the same keyid.

    * add an option to re-create a public key from a secret key. Think about
      a backup system of only the secret part of the secret key.

    * replace getkey.c#enum_secret_keys