fix learn score display

ui/learn/src/map/mapView.js

@@ -5,7 +5,7 @@ var lessons = require('../lesson/list');
 
 function makeStars(nb) {
   var stars = [];
-  for (var i = 0; i < nb; i++)
+  for (var i = 0; i < 4 - nb; i++)
     stars.push(m('i', {
       'data-icon': 't'
     }));

ui/learn/src/run/lessonStarting.js

@@ -9,7 +9,7 @@ module.exports = function(lesson, next) {
       lesson.blueprint.illustration,
       m('p', m.trust(lesson.blueprint.intro)),
       m('div.buttons',
-        m('a.light', {
+        m('a.next', {
           onclick: lesson.start
         }, "Let's go!")
       )