Remove "surfaceparm nomarks" from weapclip shader

textures/common/weapclip is often used to clip things like models or highly detailed brushes. When you would shoot with any weapon on such a clipped model/brush impact marks do not appear. This is because the weapclip shader contains the keyword surfaceparm nomarks thus absorbing any marks. I suggest removing this keyword so models can still be affected by impact marks while being clipped.