support for high contrast in simulator (#386)

* support for high contrast in simulator

* updated logic to find afterProgramPage.

sim/visuals/boardview.ts

@@ -2,9 +2,9 @@ namespace pxsim.visuals {
     mkBoardView = (opts: BoardViewOptions): BoardView => {
         return new visuals.MicrobitBoardSvg({
             runtime: runtime,
-            theme: visuals.randomTheme(),
+            theme: visuals.randomTheme(opts.highContrast),
             disableTilt: false,
-            wireframe: opts.wireframe,
+            wireframe: opts.wireframe
         });
     }
 }