 Calculating voxel volume
Take the previous script that found pixdim1, pixdim2 and pixdim3
and modify it so that it also calculates and prints out the volume of a voxel
in mm^3.
 Calculating image volume
By also finding dim1, dim2 and dim3, calculate the volume of
the whole image in mm^3.
 Field of View calculation
Print out the FOV in each direction in mm.
Look here to find the cheat.

