Add support for a multi-row array table

When arraytable was added, we had only limited support for 1 dimensional arrays. It should support both a single row and a multi-row (multi-dimensional) case.

The proposal is for the syntax:

arraytable([row|rows] ...)

if it is not specified or row, it is a single row result. If rows, then it will expect a multi-dimensional array and produce 1 row per element in the outer array.