Bug 24561: Add a Datatables api wrapper that implements filter and order embedded...

Bug 24561: Add a Datatables api wrapper that implements filter and order embedded columns

This patch adds the ability to filter and order by embedded columns.

To use it you must in JS:

$('datatable_selector').api({datatables_options})

where datatables_options are all datatables options plus:

1. embed: [list of embeddable tables]
   This option adds x-koha-embed header to request.

2. header_filter: true|false
   This option if true sets x-koha-query header with stringyfied json of filters

Oderable and searchable columns must define data option as string, otherwise filter and order won't be possible.
If you must custom the output, use the render function.

For example:

* Don't

> $('.table_selector').api({
>   columns: [
>     {
>       data: function(row, type, val, meta) {
>         return '<a href="'+row.link+'">'+row.holds.patron.firstname+'</a>';
>       },
>       orderable: true,
>       searchable: true
>     }
>   ]
> });

* Do

> $('.table_selector').api({
>   columns: [
>     {
>       data: 'holds.patron.firstname',
>       render: function(row, type, val, meta) {
>         return '<a href="'+row.link+'">'+row.holds.patron.firstname+'</a>';
>       },
>       orderable: true,
>       searchable: true
>     }
>   ]
> });

To test you must implement and test bug 20936, where it will be used.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>