code: function rotateTensor(output, tensor, rotation) {// TODO: Test this somehow...
    mat3.fromQuat(_tmpMat, rotation);
    mat3.multiply(output, _tmpMat, tensor);
    mat3.invert(_tmpMat, _tmpMat);
    mat3.multiply(output, output, _tmpMat);
  }
docs: A good description of why we need these special operations for rotating tensors can be found
  here: http://www.randygaul.net/2014/04/09/transformations-change-of-basis-matrix/.
  
  @param {mat3} output Output param.
  @param {mat3} tensor
  @param {quat} rotation