Collapse rows for internal table structures

[ctmay4]

Some schemas, like CS prostate, have 1000's of raw rows that could be collapsed to a fraction of that size in the internal representation. This is done by collapsing INPUTs that go to the same ENDPOINT. This would slow down the initialization but potentially give large speed gains in processing. I'm not sure if this optimization is worth the effort, but it would definitely help in certain situations.