Admin: Allow export of gradings list for seminars

[ottlinger]

In order to allow Sensei to do gradings more easily provide an export view to see the list of applicants in final states (BOOKED?) or selectable via UI (all/BOOKED).

First step is: HTML with with

• firstname
• lastname
• current grading
• grading since
• dojo
• city
• twa-number

If it's easy you may provide a CSV-file download as well: https://stackoverflow.com/questions/16251625/how-to-create-and-download-a-csv-file-from-php-script

[ottlinger]

https://stackoverflow.com/questions/217424/create-a-csv-file-for-a-user-in-php

header("Content-Type: text/csv");
header("Content-Disposition: attachment; filename=file.csv");

function outputCSV($data) {
  $output = fopen("php://output", "w");
  foreach ($data as $row)
    fputcsv($output, $row); // here you can change delimiter/enclosure
  fclose($output);
}

outputCSV(array(
  array("name 1", "age 1", "city 1"),
  array("name 2", "age 2", "city 2"),
  array("name 3", "age 3", "city 3")
));