recent files menu added into the main app menu, re #10335
a bit shorter lines, re #10335
updateRecentFiles when loading new files removed from here, re #10335

also improved some error messages
update recent files list from LoadDialog's accept, re #10335
small doxygen doc fix, re #10335
Merge remote-tracking branch 'origin/feature/10335_recent_files_in_main_app_menu'