Remove get_app() in favor of DI::app()

mod/fbrowser.php

@@ -78,7 +78,7 @@ function fbrowser_content(App $a)
 
 			function _map_files1($rr)
 			{
-				$a = \get_app();
+				$a = DI::app();
 				$types = Images::supportedTypes();
 				$ext = $types[$rr['type']];
 				$filename_e = $rr['filename'];

mod/item.php

@@ -848,7 +848,7 @@ function item_post(App $a) {
 function item_post_return($baseurl, $api_source, $return_path)
 {
 	// figure out how to return, depending on from whence we came
-    $a = \get_app();
+    $a = DI::app();
 
 	if ($api_source) {
 		return;

mod/message.php

@@ -499,7 +499,7 @@ function get_messages($uid, $start, $limit)
 
 function render_messages(array $msg, $t)
 {
-	$a = \get_app();
+	$a = DI::app();
 
 	$tpl = Renderer::getMarkupTemplate($t);
 	$rslt = '';

mod/settings.php

@@ -33,7 +33,7 @@ function get_theme_config_file($theme)
 {
 	$theme = Strings::sanitizeFilePathItem($theme);
 
-	$a = \get_app();
+	$a = DI::app();
 	$base_theme = $a->theme_info['extends'] ?? '';
 
 	if (file_exists("view/theme/$theme/config.php")) {