* Make InputHandler own the key cache
* Add a helper function InputHandler::cancelPressed to avoid multiple similar calls in game.cpp
* Move RandomInputHandler::step definition into cpp file
* Attempt to add registration confirmation
Using SRP auth mechanism, if server sent AUTH_MECHANISM_FIRST_SRP that means the player isn't exist.
Also tell player about the server and chosen username.
Local game has localhost as IP address of the server.
Add RenderingEngine::draw_menu_scene() to draw GUI and clouds background.
aborted -> connection_aborted
* Rewrite information message text
Client::promptConfirmRegister() -> Client::promptConfirmRegistration()
Allowing scrolling with the mousewheel when the vertical scrollbar is
hidden, unnecessarily exposes oversized containers and newlines at the
end of the text. For example try scrolling over the textareas in the
pause menu. This PR addresses the issue by requiring the scrollbar to be
visible before allowing the scrolling with the mousewheel.
