Another update for L4D2, making some changes to the AI, VAC, a few map fixes, and the SDK.

• Now ghost PZ's can never be staggered
• Enabled PZ bots 
• PZ bots use their more aggressive survival mode behavior in versus and scavenge
• Enabled finale manual spawn by default
• Fixed human PZ players not getting counted when they were dead, allowing extra PZ bots to spawn
• Reduced effectiveness of melee weapons against the Tank ( 5% of max health, from 10% )
• Fixed a case where a player who dies, then is rescued from a rescue closet, and then is revived from a ledge hang receives the secondary weapon that he lost when he was initially killed
• Improved SurvivorBot AI in cases where the bots refused to shoot through their teammates and became non-responsive
• Fixed issue with witch sometimes taking on uncommon common properties
• Fix for cheaters quitting before the vote to kick them would succeed and avoiding ban on server
• VAC banned users can now play L4D2 single-player, commentary mode and credits
• Added env_player_blocker to keep special infected from getting stuck in Dark Carnival Fair Ground
• Added navigation area that was missing in Dark Carnival Fair Ground
• Disconnected drops that were blocked by the top of a fence in Dark Carnival Fair Ground
• Deleted 2 nav areas that connected between tree trunks you can't pass through in Swamp Fever Plank Country
• Redrew ladder thinner so special infected could climb up to the roof in Swamp Fever Shanty Town
• Fixed various navigation areas in The Parish Waterfront
• Tuned spawning for difficulty in Mall
• Added missing nature/blend tooltextures added
• Added missing cs models/textures
• Added missing acunit01 model/texture
• Added missing ammo_can_02 model/texture
• Added missing patio_chair model/texture

Source