ui: preparations for user study

* added sample code
* bigger and closed arrow for inheritance edge
* fixed code hover
* lightened scope colors
* fixed interrupted scope ranges to show all lines
* fixed edge creation to correctly show recursion
* prevent aggregation edge number from floating around
* scroll to top when changing codesnippets

bin/app/data/src/sample/sample.cpp

@@ -0,0 +1,32 @@
+class Player {
+public:
+  void Do() {}
+};
+
+class Base {};
+
+class Game : public Base {
+public:
+  Game() {
+    Init();
+  }
+
+  void Init() {}
+
+  void Run() {
+    player.Do();
+  }
+
+  Player player;
+};
+
+Game* game;
+
+int main() {
+  game = new Game();
+
+  game->Run();
+
+  delete game;
+  return 0;
+}