make sure we handle a GeneralName extension value (avoids an introduced regression)
make sure ASN1::ObjectId.new(...).ln and ASN1::ObjectId.new(...).sn are correct!
improve cert.extension's value - for *extendedKeyUsage* was not returned correctly
do not keep the generator around (1st step to hopefully removing deprecated usage)
improve (composite) extension name formatting
keep cert extensions as they are added and convert them to unique oid ones as needed