Merge branch 'api_translation' into 'master'

Enable translation of strings returned by API

Adding "startup_gettext" call makes API specials categories and feeds to be sent translated
Works like a charm with official ttrss android app

See merge request !2

api/index.php

@@ -53,6 +53,8 @@
 		@session_start();
 	}
 
+	startup_gettext();
+
 	if (!init_plugins()) return;
 
 	$method = strtolower($_REQUEST["op"]);