Use BundleWithConf to avoid clone method boilerplate

rocket/src/main/scala/util.scala

@@ -21,6 +21,11 @@ object Util {
 
 import Util._
 
+abstract trait BundleWithConf extends Bundle {
+  val conf: AnyRef
+  override def clone = this.getClass.getConstructors.head.newInstance(conf).asInstanceOf[this.type]
+}
+
 object Str
 {
   def apply(s: String): UInt = {