Port stringToColor to C++.

Fixes #50.

js/util.js

@@ -1,18 +1,5 @@
 .pragma library
 
-function stringToColor(str) {
-    var hash = 0;
-    for (var i = 0; i < str.length; i++) {
-        hash = str.charCodeAt(i) + ((hash << 5) - hash);
-    }
-    var colour = '#';
-    for (var j = 0; j < 3; j++) {
-        var value = (hash >> (j * 8)) & 0xFF;
-        colour += ('00' + value.toString(16)).substr(-2);
-    }
-    return colour;
-}
-
 function pushToStack(stack, page) {
     if(page && stack.currentItem !== page) {
         if(stack.depth === 1) {