Improve nib2cib support for NSMatrix based radio groups.

Without this fix, a matrix with a target-action pair would crash when the cib was loaded due to the matrix having been replaced with a `CPView` (which cannot take a target-action pair).

Now if the matrix is for radio buttons, the action connection for the matrix is made to the `CPRadioGroup` instead and works as expected when radio selections are made.

Tools/nib2cib/NSMatrix.j

@@ -82,6 +82,7 @@ var NSMatrixRadioModeMask = 0x40000000,
                 [self setBackgroundColor:backgroundColor];
 
             self.isa = [CPView class];
+            NIB_CONNECTION_EQUIVALENCY_TABLE[[self UID]] = radioGroup;
         }
         else
         {