more general function to compare calculations

[pinarda]

specify list of calculations and datasets, perform calculations on each dataset and print out answers

like compare state but more general - make compare stats a special case of this function

[allibco]

This is for a later date :)

[allibco]

It would be great if compare stats could take in multiple sets and have them all in the table - since this is a lot easier, i may make this a separate issue