Fix global/local schema stuff and workset iterations

This fixes workset iterations, for now
Revert global schema generation stuff to original state but simply
don't use it.

We used the globalPos to create WorksetIteration, these are not
available before the post pass has run, therefore use the localPos for
now.

Properly set key positions in join,cogroup, and reduce from the
local positions.

Also add maxIterations parameter to iterateWithWorkset