[std.zh]CenterX and CenterY functions disrespect offset values

[Alucard]

As title says CenterX and CenterY functions from std.zh outright ignore HitXOffset and HitYOffset variables. I use those offsets as workaround for edge-of-the-screen limitation for lweapons in stdWeapons.zh. And CenterX and CenterY functions return wrong values, which can lead to bugs and glitches in scripted weapons. Exists in ZC 2.5.2