Hotfix v0.6.3.4

CHANGELOG v0.6.3.4 - NEW: Improved particles - NEW: Imperial unit system now available - NEW: Wet tyres automatic pre-selection, when wet track - NEW: "Ultra" option for rear mirror, with better framerate and resolution - NEW: Sound improved for F3 Metropolitana - NEW: Car glass shader improved - NEW: Showroom reflections improved - NEW: Auto-shifting help now available - FIXED: Track selection menu bug - FIXED: Texture error with disabled mirrors