GAME: Use an array for lap time signals (like debug info).
GUI: Remove GetPage, let GetOptionValue return const string.
GUI: Use separate scene node per page and return active nodes only.
This is meant to reduce the amount of gui drawables to be processed
by the graphics system, given that only few of them are active/visible
at the same time.
GAME: Remove USE_STATIC_OPTIMIZATION_FOR_TRACK define.