Fix issues in .clone(); now all of clone.t passes again.

src/core/Mu.pm

@@ -215,9 +215,21 @@ my class Mu {
         $self.HOW.can($self, $name)
     }
 
-    method clone() {
+    method clone(*%twiddles) {
         my $cloned := pir::repr_clone__PP(nqp::p6decont(self));
-        # XXX Probably need to clone containery things a level deeper.
+        for self.^attributes() -> $attr {
+            my $name := $attr.name;
+            my $package := $attr.package;
+            unless pir::repr_get_primitive_type_spec__IP($attr.type) {
+                my $attr_val := nqp::getattr($cloned, $package, $name);
+                nqp::bindattr($cloned, $package, $name, pir::repr_clone__PP($attr_val.VAR))
+                    if nqp::iscont($attr_val);
+            }
+            my $acc_name := $name.substr(2);
+            if $attr.has-accessor && %twiddles.exists($acc_name) {
+                nqp::getattr($cloned, $package, $name) = %twiddles{$acc_name};
+            }
+        }
         $cloned
     }