Function align_to_ras 

fn align_to_ras(
    source: &[f64],
    source_dims: [usize; 3],
    dims: [usize; 3],
    perm: [usize; 3],
    flip: [bool; 3],
) -> Vec<f32>

Gather a column-major (nx, ny, nz) volume into a C-order RAS-oriented f32 buffer.