Due to the changes in CA.pl in 0.9.8 (use of -self_sign) a slightly different
technique is used to ensure that 'ca' uses the next serial number. It
now initializes the serial number using 'openssl x509 -next_serial'.
This allows intermediate CAs to be created more easily.
PKCS12_create() now checks private key matches certificate.
Fix typo in x509 app.
Update docs.
New function ASN1_STRING_to_UTF8() converts any ASN1_STRING
type to UTF8.