Implement basic multithreading support

A few CPU heavy operations, which are opening an archive and displaying
a selected Activity, have been moved to another thread to avoid having
long-running operations on the main thread.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/archive_parser.h b/src/archive_parser.h
index c206087..7377120 100644
--- a/src/archive_parser.h
+++ b/src/archive_parser.h
@@ -28,11 +28,11 @@ public:
 
     Archive(QString outbox_filename, ArchiveType archive_type);
     ~Archive();
-    InitError init();
+    std::variant<QString, InitError> init();
 
     void update_status_list(ViewStatusTypes allowed_types, QListWidget *parent);
-    QString get_html_status_info(int status_index, int text_zone_width, StatusType status_type, QLocale* locale);
-    QString get_html_status_text(int status_index);
+    const QString get_html_status_info(int status_index, int text_zone_width, StatusType status_type, QLocale* locale);
+    const QString get_html_status_text(int status_index);
 private:
     QString outbox_filename;
     QDir archive_root_dir;