* ENT-6357: Deserialize LedgerTransaction elements for each Contract.verify().
* Lock the LedgerTransaction and NetworkParameters objects down for contract verification.
* Refactor BasicVerifier to be package private instead of public.
* Simplify verifyConstraints() operation.
* Review fixes: replace HashSet with LinkedHashSet, and add signing parties to commands via mapIndexed.
* Ensure tests also run notary nodes "out of process".
* Streamline SerializationContext switching.
* Cache deserialised cryptographic instances during contract verification.
* Invoke Class.forName() instead of ClassLoader.loadClass() to reduce contention on the system classloader's lock.
* Deserialization cache key now pre-computes its hash code.
* Allow AttachmentsClassLoader to be used concurrently.
* Cache all Envelope objects for reuse during contract verification.
* Generate CertPathProxy hash code using conventional algorithm.
* Adjust CustomSerializer.Proxy to allow better access to SerializationContext.
