A new beta branch has been launched for the purpose of testing new / experimental features. For details on this and how to opt-in please see this guide:
https://steamcommunity.com/sharedfiles/filedetails/?id=580567274

Changes in this version (Since live branch s1.1.5)------------------------------------------------------------------------ Ported to latest source engine version
- includes but not limited to "Client/server memory improvements"

New gamemode: Survival
- An infinite hold out senario where players must survive waves of zombies of ever increasing difficulty, whist resuppling with in-between waves with random weapons.

New map: csv_house
- Created for use with the survival mode

Added option for server admins to disable parts of the vote system

Added an option for server admins to enable teamkill punishment (via sv_teamkillpunish)
- attacking players recieve the damage they inflict and then some

Improvements to sentry / chest planting on un-even surfaces (such as terrain)

Sentry / chest pickup detection improvments (and can now be picked up with use key)

Improvements to grenade pickups

Tweak to bomb plant hint UI (stopping bottom of text being cut off on certain resolutions so that E looks like F)

Updated German translation courtesy of: Swordman

French translation encoding fix------------------------------------------------------------------------
EDIT: Patch 22/12/15
Various fixes relating to survival mode:
- map change
- vote system
- weapon pickup / balances (now more weighted towards primaries in later waves)