Decomplect Aggreagtor

Currently handling two functions:
1) Combine an aggregates with a raw inputs (I+A = A)  OR create an aggregate from two inputs (I+I=A)(Combine)
2) Combining two aggregate values (A+A=A)  (Rollup)

The two do not need to be tied.  They are related, but there are times that the same combine has different logical combine rollups (sum on combine, but max on rollup...for example).
