Sentinel Table Expansion Enhancement

[tyBouch]

As it stands the Sentinel table object relies on fixed tags/selectors for grabbing columns, rows, headers, etc from tables. This means non standard tables, such as ones that use different tags for cells than headers, will not be correctly constructed.

To better allow expansion these could be replaced with By objects so the user can override the selectors used. Allowing for complex non standard tables to use the existing logic.