Load $nb/2 articles when articles are unfolded

See https://github.com/marienfressinaud/FreshRSS/issues/559

app/Controllers/indexController.php

@@ -83,6 +83,11 @@ class FreshRSS_index_Controller extends Minz_ActionController {
 		$nb = Minz_Request::param ('nb', $this->view->conf->posts_per_page);
 		$first = Minz_Request::param ('next', '');
 
+		$ajax_request = Minz_Request::param('ajax', false);
+		if ($ajax_request == 1 && $this->view->conf->display_posts) {
+			$nb = max(1, round($nb / 2));
+		}
+
 		if ($this->view->state === FreshRSS_Entry::STATE_NOT_READ) {	//Any unread article in this category at all?
 			switch ($getType) {
 				case 'a':

app/layout/layout.phtml

@@ -13,6 +13,7 @@
 	if (!empty($this->nextId)) {
 		$params = Minz_Request::params();
 		$params['next'] = $this->nextId;
+		$params['ajax'] = 1;
 ?>
 		<link id="prefetch" rel="next prefetch" href="<?php echo Minz_Url::display(array('c' => Minz_Request::controllerName(), 'a' => Minz_Request::actionName(), 'params' => $params)); ?>" />
 <?php } ?>

app/views/helpers/pagination.phtml

@@ -9,7 +9,10 @@
 <ul class="pagination">
 	<li class="item pager-next">
 	<?php if (!empty($this->nextId)) { ?>
-		<?php $params['next'] = $this->nextId; ?>
+		<?php
+			$params['next'] = $this->nextId;
+			$params['ajax'] = 1;
+		?>
 		<a id="load_more" href="<?php echo Minz_Url::display(array('c' => $c, 'a' => $a, 'params' => $params)); ?>">
 			<?php echo _t('load_more'); ?>
 		</a>