GRIDROTATE Rotate grid. 
[ GRID ] = GRIDROTATE( GRID, TH, AX ) Applies rotation angle TH 
- (radians) to grid points around the origin (in 3D around axis AX
 - 1 = x-axis (default), 2 = y-axis, 3 = z-axis). The input argument GRID can either be a grid struct or simply an array of coordinates. Normals will also be recalculated in the case of a grid struct with boundary information.
 
- See also
 - gridextrude, gridmerge, gridrevolve, gridscale