Ir proximity in simulator (#299)

* support for IR proximity

* fixing build issue

* missing break

* remove auto-start of sensor

* setting mode on onEvent

* flooring slider value

* bump up proximity

* fixing threshold blocks

sim/visuals/nodes/infraredview.ts

@@ -0,0 +1,10 @@
+/// <reference path="./moduleView.ts" />
+
+namespace pxsim.visuals {
+    export class InfraredView extends ModuleView implements LayoutElement {
+
+        constructor(port: number) {
+            super(INFRARED_SVG, "infrared", NodeType.InfraredSensor, port);
+        }
+    }
+}