* improve iobuf by reading more than one byte at once,
      this shoud espceially done for the buffer in the chain.
    * add a way to difference between errors and eof in the underflow/flush
      function of iobuf.
    * add checking of armor trailers
    * look for a way to reuse RSA signatures
    * remove all "Fixmes"
    * speed up the RIPE-MD-160
    * add signal handling
    * enable a SIGSEGV handler while using zlib functions

    * complete cipher/cast.c
    * complete cipher/dsa.c

    * add g10 stuff to Mutt's pgpinvoke.c

    * Burn the buffers used by fopen().

    * bug: g10/trustdb.c#build_sigrecs called to often by do_list_path
      and remove the bad kludge. Maybe we should put all sigs into the trustdb
      and mark them as valid/invalid/nopubkey, and how do we check, that
      we have a self-signature -> put this stuff into a kind of directory
      record, as it does not belong to the pubkey record?