Fixes, improvements, more damage checks

[NexiusTailer]

1. Checks for entering/leaving race checkpoints if player isn't spawned
2. Block OnPlayerGiveDamage for vehicle drivers as there is no known cases when they call it themselves (any damage from driver e.g. carpark and so on are handled by OnPlayerTakeDamage from damaged player only)
3. Stricter limit on the damage hits per shot
4. Minor fixes and corrections