title: SabreCSG in Unity3D can't make build (error CS0246: The type or namespace name '***' could not be found)
body: <p>I have tried in several ways (even created empty project and installed sabreCSG in my unity).
  I am using unity 2017.4.3, Unity 2019.3.6 and Unity 2020 latest version as well.
  It runs normally in editor but when I tried to make build or stand-alone exe, It gives me these errors.
  Where is mistake? My player settings are also normal</p>
  <p>error CS0246: The type or namespace name '***' could not be found (are you missing a using directive or an assembly reference?)</p>
  <p><a href="https://i.stack.imgur.com/nwgMs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nwgMs.png" alt="enter image description here" /></a>
  <a href="https://i.stack.imgur.com/RJOAD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RJOAD.png" alt="enter image description here" /></a></p>