Revs for Sinclair ZX Spectrum 48K v2.2

Optiomizations and crashed AI car is pushed to track side instead staying in middle of track as original code intended but it never works like that.

Revs for Sinclair ZX Spectrum 48K v2.1

Optimizations, off track rendering fix and added speed MPH into HUD.

Revs for Sinclair ZX Spectrum 48K v2.0

Complete rewrite based on C64 timings. Runs around 6FPS in realtime.