Realistic Engine Sound

New Things

• Added subtitle support.
• Distinct up-shift / down-shift sound.
• Added blink logic in the RPM HUD that plays when you are close to shifting gears.

Changed Things

• Added texture for Left and Right input instead of having one for both.
• Sound namespace moved from engine_sounds: to realistic_engine:.
• Made the Speed HUD and the RMP HUD use the same texture folder.
• Minor tweaks to steer input textures.
• Max ping icon now shows at <= 20 ms.
• Minor layout changes.