[EM] SAV generalized to any kind of Range Ballots

[fsimmons at pcc.edu]

The SAV score of a range ballot r for a coalition C can be written as a fraction with numerator

Sum over x in C of r(x), 

and denominator

Sum over all x of r(x).

Note that when r is an approval ballot the numerator is the number of alternatives in C approved by r, and 
the denominator is the total number of alternatives approved by r, so this is a straightforward 
generalization of SAV to range ballots.