Add linear redux evaluators

Reference issue

What does this implement/fix?

Linear access coeff(index) allows an expression to be evaluated as if it were a 1d array. This conveys many benefits, including simplified traversal, simple alignment logic, etc. At worst, it has the same performance as 2d access coeff(row,col), but is usually faster. The redux evaluators do not implement linear access for the unrolled scalar, unrolled vectorized (currently pseudo linear access), and "rolled" scalar traversals. This patch adds those traversals.

Additional information