Demo of showing loading progress, WaitForRenderAndCall utility, new TCastleTouchNavig

[DP News-Robot]

We have new TUIState.WaitForRenderAndCall utility, especially useful to implement loading inside TUIState descendant. Our examples/user_interface/zombie_fighter features now a demo showing loading progress (as a descendant of TUIState, which is our advised approach for loading screens now). Whole examples/user_interface/zombie_fighter was remade to use editor. We have a new UI control, available from code and in editor: …