Add new APIs EC_curve_nist2nid and EC_curve_nid2nist which convert

between NIDs and the more common NIST names such as "P-256". Enhance
ecparam utility and ECC method to recognise the NIST names for curves.
(backport from HEAD)

apps/ecparam.c

@@ -402,6 +402,9 @@ bad:
 			}
 		else
 			nid = OBJ_sn2nid(curve_name);
+
+		if (nid == 0)
+			nid = EC_curve_nist2nid(curve_name);
 	
 		if (nid == 0)
 			{