Some minor fixes

Fixes to DropItems include held item, holstered item, armour, handcuffs
and more. Also made the code clearer to read.

Added a "/dropall" command for surrendering gear.

Removed some old code that resulted in Z positions becoming corrupted
when loading if outside the map boundaries.

Implemented a fix for GetPlayerButtonList for tents (not in SIF yet due
to y_hooks issue).

Extended the time required to hold the crouch key to sit down.

Fixed nitro and hydraulics hack detector, it now removes the car mods
once the player is banned to ensure players who enter the vehicle aren't
banned too.