fix for blended material names that contain capital letters. All are converted to lowercase for consistency with material naming that comes from the mixing table.
if a reactor is 2D, the z bounds for the volume calc are reset to 1 so that the reported volume corresponds to the 2D area. Tests have been added for this change.
Formatting for the volume information in the summary is updated so that the volume numbers are more readable and long material/cell names don't misalign.