Editing Variable-Length Line Item Edits (section)

==== Line item group container ====

One `div` (or `section`) to act as a container for the line items.
* This `div` should be outside the include file for the individual line items, either in its own include file, or placed directly in the details and editing include file.
* CSS class is `line-items-container`.
* Include a `button` for adding new line items (class `add-line-btn`).
** CSS class is `add-line-btn`.
** `data-pid` attribute contains the parent record's id.
** `data-type` attribute contains the name of the PHP class that will be used to save edits to the line.