Validate SignedObject DER encoding using incidences schema.

Validate SignedObject DER encoding using incidences schema.

-asn1c doesn't have a DER decoder, but it has DER encoders. Once the data is BER decoded, encode it again as DER and compare against the original data, the difference (if there's one) will be at ASN1 TLVs.
-Create new incidence 'incid-obj-not-der-encoded' to handle such error.
-Update docs: RFC 6488 100% compliance, new incidence description.
-Add new incidence to configuration example (examples/config.json).