1. Tidy the code, integrate with SSLeay. The ASN1 stuff should
   go into crypto/asn1, it is possible that some equivalents already exist,
   for example I found out PKCS#7 DigestInfo is equivalent to
   X509_SIG in SSLeay. Also the error codes are currently bogus (pick a
   number any number ...) I'm not sure if this can be done cleanly without
   making it part of SSLeay itself, if anyone knows different let me know.
2. Maintain compatability with any Netscape variations.
3. Add support for "proper" PKCS#12. This shouldn't be too hard because some
   parts are very similar (as you would expect since PKCS#12 is based on PFX).
