Move simple-mode settings customization check into a separate file

CURA-4333

Simple-mode is a special mode so it makes more sense to put those code
in a separate file instead of in the more generic MachineManager.

cura/Settings/SimpleModeSettingsManager.py

@@ -0,0 +1,55 @@
+# Copyright (c) 2017 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
+from PyQt5.QtCore import QObject, pyqtSignal, pyqtProperty
+
+from UM.Application import Application
+
+
+class SimpleModeSettingsManager(QObject):
+
+    def __init__(self, parent = None):
+        super().__init__(parent)
+
+        self._machine_manager = Application.getInstance().getMachineManager()
+        self._is_profile_customized = False
+
+        self._machine_manager.activeStackValueChanged.connect(self._updateIsProfileCustomized)
+
+    isProfileCustomizedChanged = pyqtSignal()
+
+    @pyqtProperty(bool, notify = isProfileCustomizedChanged)
+    def isProfileCustomized(self):
+        return self._is_profile_customized
+
+    def _updateIsProfileCustomized(self):
+        user_setting_keys = set()
+
+        if not self._machine_manager.activeMachine:
+            return False
+
+        global_stack = self._machine_manager.activeMachine
+
+        # check user settings in the global stack
+        user_setting_keys.update(set(global_stack.userChanges.getAllKeys()))
+        # check user settings in the extruder stacks
+        if global_stack.extruders:
+            for extruder_stack in global_stack.extruders.values():
+                user_setting_keys.update(set(extruder_stack.userChanges.getAllKeys()))
+
+        for skip_key in self.__ignored_custom_setting_keys:
+            if skip_key in user_setting_keys:
+                user_setting_keys.remove(skip_key)
+
+        has_customized_user_settings = len(user_setting_keys) > 0
+
+        if has_customized_user_settings != self._is_profile_customized:
+            self._is_profile_customized = has_customized_user_settings
+            self.isProfileCustomizedChanged.emit()
+
+    # A list of settings that will be ignored when check whether there is any custom settings.
+    __ignored_custom_setting_keys = ["support_enable",
+                                     "infill_sparse_density",
+                                     "gradual_infill_steps",
+                                     "adhesion_type",
+                                     "support_extruder_nr"]