Replace clone with reference

This avoids an unnecessary allocation and memory copy
when printing the empty panel during line wrapping.

src/printer.rs

@@ -705,7 +705,7 @@ impl<'a> Printer for InteractivePrinter<'a> {
                                             background_color
                                         ),
                                         self.ansi_style.to_reset_sequence(),
-                                        panel_wrap.clone().unwrap()
+                                        panel_wrap.as_ref().unwrap()
                                     )?;
 
                                     cursor = 0;