Added shortcuts

scripts/keyboard.js

@@ -0,0 +1,16 @@
+function Keyboard()
+{
+  this.listen = function(event)
+  { 
+    console.log(dotgrid);
+    console.log(event.keyCode);
+
+    switch (event.key || event.keyCode) {
+      case 65 : dotgrid.draw_arc_a(); break;
+      case 83 : dotgrid.draw_arc_c(); break;
+      case 68 : dotgrid.draw_line(); break;
+      case 70 : dotgrid.reset(); break;
+
+    }
+  }
+}