Added ConVar cl_fixmodelinterpolationartifacts, a feature backported from HL25 update
It fixes interpolation artifacts (visual stuttering) for animated models on moving platforms (e.g., a scientist on a train)
Added the -nosingle launch option to allow running multiple game instances, with connections restricted to servers where sv_chats is enabled
Added cross-compatibility for CS 1.6 and Condition Zero games in the ServerBrowser