Support printing user's itinerary

- Define print.css with media=print type (note: could've been handled with
  @media queries)
- Define printPage port to interop with window.print() JS function
- Support UI.wrapNoPrint to wrap components with a the no-print CSS

client/print.css

@@ -0,0 +1,3 @@
+.no-print {
+  display: none;
+}