prop-accurate combine metal

prop-accurate combine metal replaces the combine metal with new textures based off of the combine props to hopefully fix the weird discrepancy in coloring that the two have. i've always noticed this and thought it was weird (combine prop textures are dark bluish/purple with reddish brown rust, while combine world textures are bluish grey with cyan rust) credits valve, for the original textures. me, for the edits and everything else.