message: Fixes memory leak due to ImGui context not being destroyed.
diff: @@ -50,7 +50,9 @@ namespace vks
  io.FontGlobalScale = scale;
  }
  - UIOverlay::~UIOverlay() { }
  + UIOverlay::~UIOverlay() {
  + ImGui::DestroyContext();
  + }
  /** Prepare all vulkan resources required to render the UI overlay */
  void UIOverlay::prepareResources()
  @@ -397,7 +399,6 @@ namespace vks
  void UIOverlay::freeResources()
  {
  - ImGui::DestroyContext();
  vertexBuffer.destroy();
  indexBuffer.destroy();
  vkDestroyImageView(device->logicalDevice, fontView, nullptr);
  