The round manager has been rewritten to improve code quality and reusability and is now using meta-classes, which slightly improves overall performance. For addons that hook into the gamemode, this means that GAMEMODE.RoundManager is only valid after GM:Initialize() has been run.
Additionally the Prop Hunt SMG has been slightly changed and now fires at a rate of 0.075 (from 0.1), but deals only 4 damage (from 5), which makes it near identical to the standard Half Life 2 SMG. It will now deal 53.33 DPS instead of 50 DPS like before, while keeping the accuracy and extra features as is.