Version 15 comes with GMod update 102. Changes:

New features

• Traitor/Detective equipment has been split into slot 7 and slot 8. You can carry one of each type. This means you can carry both a Silenced Pistol and a Teleporter, for example.
• "Visualizer" weapon for Detectives. Drop it near a corpse that was killed with a gun, and it will show you where the shooter was when he shot the victim. You can pick it up again afterwards, it's infinite use.
• Teleporter is available to Detectives again, as it was a long time ago.
• New quickchat command for alive-checking.

Balance

• Knife no longer kills instantly. Two stabs are required to kill a full-health victim. Note that the knife stays in your inventory until you kill someone with it (or drop it), you don't need two different knives or something. Knives stuck in corpses no longer have DNA. Discussion thread is here, more balancing will happen in future updates where necessary to compensate for the weaker knife.
• Increased range on Knife stab to make it more reliable.
• Corpses must be identified before the killer's DNA can be retrieved.

Fixes

• Fixed flashlight exploit used to silence any gun, by preventing the flashlight click sound from ever playing. The delay on toggling your flashlight has been removed as it is no longer needed.
• Fixed Last Words exploit where a non-numeric id let you send messages and ghost.
• Fixed C4 removal also deleting DNA samples retrieved from that C4.
• Removed health station blinking light, it was glitchy.
• Fixed health station handling melee damage differently from gun damage.
• Fixed auto-bans using Sourcemod compatibility not having a properly quoted reason set.
• Fixed traps in a map that dealt drowning or bullet damage not properly listing both the trap name and the attacker, when ttt_damageowner was used for that purpose.
• Menu text that mentions the key for something now shows the actual key you've bound, rather than the gmod default.

Mapping

• Added ttt_credit_adjust entity, for giving or taking credits from a player. Check the mapping guide for the updated FGD, as well as more information on the new entity.

Server/admin

• Experimental: ttt_karma_persist (def. 0). When enabled, player's karma values are stored persistently at the end of the round or when a player disconnects, and loaded when they join. Hence, karma becomes persistent across map changes and play sessions. Note that this feature has known issues, such as the karma not resetting when someone is autobanned. This will be addressed soon in the latest SVN build, and of course the next gmod update.