new funcs in navigation to export instructions

lib/Navigation/route.cpp

@@ -20,13 +20,17 @@ void Route::addPointToRoute(Point point) {
 }
 
 Point Route::startRoute() {
+    if (this->points.size() < 1)
+        return Point(0, 0);
     *this->it = this->points.begin();
     return **this->it;
 }
 
 Point Route::getNextPoint() {
-    if (*this->it != this->points.end())
+    if (*this->it != this->points.end()) {
+        this->it++;
         return **this->it;
+    }
     else
         return Point(0, 0);
 }