fix #662

[caver456]

• show loginDialog (which calls loadOperators) for continued incidents, even though options dialog is not shown at startup for confinued incidents
• make sure loginDialog is not shown until after the main window is shown, and not until after the options dialog is closed (if shown at startup)
• also call loadOperators in loginDialog.init
• modify saveOperators to skip the save operation if the operators list is empty - which should never happen anymore, with the above fixes in place