R10 - almost final update :D

- Added SendInvalidPlayerSync to crash raksamp
- Added IsPlayerCheckpointActive, IsPlayerRaceCheckpointActive
- Fixed bug with IsPlayerConnected, this function will check 4byte of
playerid not only 2
- Improved hooking system, now hooks only will run from gamemode

TODO: Fix GetPlayerWeapon() bug which caused by
OnPlayerStatsAndWeaponsUpdate