Permit Org.BouncyCastle.Crypto.Generators.ECKeyPairGenerator to save cur...

...ve names, per Jira BMA-101

When publicKeyParamSet is left null, then GenerateKeyPair() does not look up the parameter set to try to save the curve name.  When it's set, the constructor overloads for ECPublicKeyParameters and ECPrivateKeyParameters take the curve name and don't bother with explicit encoding.

This resolves Jira issue BMA-101.
Realistically, this problem could also be solved by removing the locally-scoped "oid" variable, and renaming every "oid" to "publicKeyParamSet" in this block and the preceding switch.

The issue of explicit curve parameter encoding only occurs in circumstances where the KeyGenerationParameters is not an ECKeyGenerationParameters (that is, the client of the library specifies a strength and lets the library sort it out).  If ECKPG is initialized with an ECKeyGenerationParameters which has been constructed with a specific OID, then the publicKeyParamSet is properly set; if it's initialized with an ECKeyGenerationParameters which has been constructed with ECDomainParameters, then publicKeyParamSet remains null and the explicit encoding occurs properly.

But, this would cause a problem for those people who need explicit encoding of curve parameters that have names.  FindECCurveByOID is internal, not public.

Perhaps there needs to be a subclass of AsymmetricCipherKeyPair that can hold EC keypairs, and perform normalization (naming) and denormalization (un-naming) on the curves in the key objects?