astrodatagui: close all database connections properly before exiting

astrodatagui/AstrodataGUI.py

@@ -11,6 +11,9 @@ class AstrodataGUI(QtWidgets.QMainWindow):
         classFileDir = os.path.dirname(os.path.abspath(__file__))
         absUiFilePath = os.path.join(classFileDir, "astrodatagui.ui")
         uic.loadUi(absUiFilePath, self)
+
+        self.actionExit.triggered.connect(self.actionExitTriggered)
+
         self.show()
 
         self.loadDB()
@@ -25,4 +28,10 @@ class AstrodataGUI(QtWidgets.QMainWindow):
 
     def showErrorMessage(self, title: str, msg: str):
         print(title)
-        print(msg)
+        print(msg)
+
+    def actionExitTriggered(self):
+        for starDB in StarDB.getAllInstances():
+            starDB.close()
+
+        exit()