Allow player to continue playing after the end of a turn. (#3526)

This PR:

Keeps track of time spent in mission 

Introduces a new "turnless mode" setting, which activates the following:
- At the end of a mission, fast forwards through the time spent in the
mission, skipping any combat (which has already been tracked through
state.json)
- Removes killed flights from the ATO
- Does not start a new turn, instead allows the player to continue the
current turn.

qt_ui/widgets/QTopPanel.py

@@ -50,10 +50,7 @@ class QTopPanel(QFrame):
         self.conditionsWidget = QConditionsWidget(sim_controller)
         self.budgetBox = QBudgetBox(self.game)
 
-        pass_turn_text = "Pass Turn"
-        if not self.game or self.game.turn == 0:
-            pass_turn_text = "Begin Campaign"
-        self.passTurnButton = QPushButton(pass_turn_text)
+        self.passTurnButton = QPushButton(self._pass_turn_button_text(self.game))
         self.passTurnButton.setIcon(CONST.ICONS["PassTurn"])
         self.passTurnButton.setProperty("style", "btn-primary")
         self.passTurnButton.clicked.connect(self.passTurn)
@@ -120,11 +117,9 @@ class QTopPanel(QFrame):
         self.factionsInfos.setGame(game)
 
         self.passTurnButton.setEnabled(True)
-        if game and game.turn > 0:
-            self.passTurnButton.setText("Pass Turn")
+        self.passTurnButton.setText(self._pass_turn_button_text(game))
 
         if game and game.turn == 0:
-            self.passTurnButton.setText("Begin Campaign")
             self.proceedButton.setEnabled(False)
         else:
             self.proceedButton.setEnabled(True)
@@ -283,3 +278,11 @@ class QTopPanel(QFrame):
 
     def budget_update(self, game: Game):
         self.budgetBox.setGame(game)
+
+    def _pass_turn_button_text(self, game: Game) -> None:
+        if game and game.turn > 0:
+            if game.settings.turnless_mode:
+                return "End Turn"
+            else:
+                return "Pass Turn"
+        return "Begin campaign"

qt_ui/windows/QLiberationWindow.py

@@ -571,7 +571,8 @@ class QLiberationWindow(QMainWindow):
         if state is not TurnState.CONTINUE:
             GameOverDialog(won=state is TurnState.WIN, parent=self).exec()
         else:
-            self.game.pass_turn()
+            if not self.game.settings.turnless_mode:
+                self.game.pass_turn()
             GameUpdateSignal.get_instance().updateGame(self.game)
 
     def open_tgo_info_dialog(self, tgo: TheaterGroundObject) -> None: