GUI: Reimplement Head-Up Display as a gui page.
GAME: Move hud update code into a separate function.
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.
GUI: Remove unused Active() function.
GUI: Make slider image property explicit.
Slider can be seen as a special type of image.
GUI: Add radial slider widget.
Fill mode not implemented yet.
GAME: Adjust normalized rpm and speed to match tacho/speedometer.
Tachometer range is 8000-20000 in 2000 rpm steps.
Speedometer range is 120-320 in 40 kph/mph steps.
GRAPHICS: Use SetAxisAngle when transforming vertex array data.
GAME: Remove max speedometer calculation.
Stick to the 120-320 range, independent of speed units.
GUI: Add screen center relative widget positioning.
Using center-left, center-right properties.
GAME: Implement HUD page selection.
GUI: Expose widget visible property to gui scripting.
This can be seen as somewhat redundant to the opacity property, allows hiding widgets independent of opacity value though (will be used by input graph).
GUI: Don't update label if text string didn't change.
GUI: Reimplement input graph using gui scripting.
GUI: Remove old hud and inputgraph implementations.
Merge branch 'hud'