keep track of opened, saved file to appropriately prompt save xml when needed, add Save As menu option

daemon/core/gui/menuaction.py

@@ -90,6 +90,7 @@ class MenuAction:
         if file_path:
             self.add_recent_file_to_gui_config(file_path)
             self.app.core.save_xml(file_path)
+            self.app.core.xml_file = file_path
 
     def file_open_xml(self, event: tk.Event = None):
         init_dir = self.app.core.xml_dir
@@ -196,3 +197,4 @@ class MenuAction:
     def new_session(self):
         self.prompt_save_running_session()
         self.app.core.create_new_session()
+        self.app.core.xml_file = None

daemon/core/gui/menubar.py

@@ -57,6 +57,7 @@ class Menubar(tk.Menu):
         )
         self.app.bind_all("<Control-o>", self.menuaction.file_open_xml)
         menu.add_command(label="Save", accelerator="Ctrl+S", command=self.save)
+        menu.add_command(label="Save As", command=self.menuaction.file_save_as_xml)
         menu.add_command(label="Reload", underline=0, state=tk.DISABLED)
         self.app.bind_all("<Control-s>", self.save)