Added some late stage features based on tester feedback

• Always allow a player to continue to the next race, even if they didn't place in the top 3, but:
• Bigger prizes for placing in top 3 to allow better upgrades.
• Grand Prix mode now has an after-race results screen, followed by a table of overall standings.
• Added pause mode during races in case you need to pick your nose.
• Increased starting stats for vehicles to further differentiate their performance characteristics.
• If a player retries a race after completing it, they are gifted 800 $lipbux, as a treat.
• Various visual tweaks.