Version 13 rolled in with a recent GMod update. The detailed changes:

New features

• Pushing someone into a trap or other map-based death will now count as your kill.
• Rifle now has a scope texture and reworked crosshair while zoomed in.
• Optional sound cues when a round starts and ends can be enabled in the Settings menu. This is meant for people who read a book while dead or something.
• Numerous icons have been tweaked a bit in various ways.

Balance

• C4 beep frequency is now dependent on the time remaining on its fuse.
• C4 beep loudness is now dependent on its initial fuse time. So a 10 minute C4 is quieter than a 1 minute C4, even if they both have 30s on the clock. Every failed disarm attempt makes it louder, for effect.
• Karma now has a stronger effect on your damage penalty for higher karma values. Previously any karma above 800 was pretty much equal to 1000, now you'll get a more significant damage penalty sooner. See server/admin section below.

Fixes

• Fixed Magneto-stick allowing you to throw players who stood on the prop you carry, which enabled map exploits. You will now drop the prop as soon as someone stands on it.
• Fixed Magneto-stick not respecting FVPHYSICS_NO_PLAYER_PICKUP. This was allowing it to pick up constrained entities (dm_richland seesaw) that would then glitch out.
• Fixed DNA sample disappearing if the originating corpse was burned or otherwise destroyed.
• Optimized HUD drawing code, might help performance on low-end computers.
• The "T" icon above fellow traitors is now more opaque and easier to see.
• Replaced the "you are idle" dialog window. This should fix issues where you couldn't click the buttons on it in some situations.
• Fixed error when sorting on the alive-ness column in the round report.
• Fixed an equipment buy overriding a pending order, when you ordered something in a constrained space and then bought something else immediately after. The second purchase will now be prevented.
• Fixed various errors related to GMod's new userdata type checks.
• Fixed possible error when a player was killed while charging his Newton Launcher.

Mapping

• Magneto-stick no longer has infinite force, so traps should no longer be blockable as long as you make the physics objects (rolling boulders and whatnot) involved very heavy. If you find a situation where it's still problematic, let me know.

Server/admin

• ttt_karma_strict (def. 1): Enables the new stricter damage penalties. Set this to 0 to return to the old stuff. Keep in mind that the stricter damage penalties are more in line with the strict anti-RDM policy most servers have, and if your server has that you might just want to keep this enabled.
• ttt_voice_drain (def. 0): Experimental. Enables a voicechat battery that empties as a player uses voice and recharges when he doesn't. If emptied, the player cannot speak for a few seconds. Meant to discourage micspamming. I need feedback based on real-world mic usage about how well this works out, and about possible tweaks for the convar settings:
  
  • ttt_voice_drain_normal (def. 0.2): Battery drain per tick of voicechat for non-admins.
  • ttt_voice_drain_admin (def. 0.05): Battery drain per tick of voicechat for admins.
  • ttt_voice_drain_recharge (def. 0.05): Battery recharge per tick of no voicechat.
• Damagelog now takes a player's Karma damage penalty into account for the damage values.