joystickPagination: Add small control to flip axes

Don't know if that's the final solution. There's probably
a better (more visible) one.

refs #2640

application/views/scripts/joystickPagination.phtml

@@ -10,6 +10,15 @@ $showText = $this->translate('%s: Show %s %u to %u out of %u', 'pagination.joyst
 $xAxisPages = $xAxisPaginator->getPages('all');
 $yAxisPages = $yAxisPaginator->getPages('all');
 
+$flipUrl = Url::fromRequest();
+$flipUrl->setParam('flipped', (int) ! $flipUrl->getParam('flipped'));
+if ($flipUrl->hasParam('page')) {
+    $flipUrl->setParam('page', implode(',', array_reverse(explode(',', $flipUrl->getParam('page')))));
+}
+if ($flipUrl->hasParam('limit')) {
+    $flipUrl->setParam('limit', implode(',', array_reverse(explode(',', $flipUrl->getParam('limit')))));
+}
+
 $totalYAxisPages = $yAxisPaginator->count();
 $currentYAxisPage = $yAxisPaginator->getCurrentPageNumber();
 $prevYAxisPage = $currentYAxisPage > 1 ? $currentYAxisPage - 1 : null;
@@ -79,7 +88,20 @@ $nextXAxisPage = $currentXAxisPage < $totalXAxisPages ? $currentXAxisPage + 1 :
         <?= $this->icon('left-open'); ?>
       <?php endif ?>
       </td>
+      <?php if ($this->flippable): ?>
+      <td><?= $this->qlink(
+        '',
+        $flipUrl,
+        null,
+        array(
+          'icon'                => 'arrows-cw',
+          'data-base-target'    => '_self',
+          'title'               => $this->translate('Flip grid axes')
+        )
+      ) ?></td>
+      <?php else: ?>
       <td>&nbsp;</td>
+      <?php endif ?>
       <td>
       <?php if ($nextXAxisPage): ?>
         <?= $this->qlink(