Move MultiBuildPlateModel into Models folder

cura/Machines/Models/MultiBuildPlateModel.py

@@ -0,0 +1,50 @@
+from PyQt5.QtCore import pyqtSignal, pyqtProperty
+
+from UM.Application import Application
+from UM.Scene.Selection import Selection
+from UM.Qt.ListModel import ListModel
+
+
+class MultiBuildPlateModel(ListModel):
+
+    maxBuildPlateChanged = pyqtSignal()
+    activeBuildPlateChanged = pyqtSignal()
+    selectionChanged = pyqtSignal()
+
+    def __init__(self, parent = None):
+        super().__init__(parent)
+
+        self._application = Application.getInstance()
+        self._application.getController().getScene().sceneChanged.connect(self._updateSelectedObjectBuildPlateNumbers)
+        Selection.selectionChanged.connect(self._updateSelectedObjectBuildPlateNumbers)
+
+        self._max_build_plate = 1  # default
+        self._active_build_plate = -1
+
+    def setMaxBuildPlate(self, max_build_plate):
+        self._max_build_plate = max_build_plate
+        self.maxBuildPlateChanged.emit()
+
+    ##  Return the highest build plate number
+    @pyqtProperty(int, notify = maxBuildPlateChanged)
+    def maxBuildPlate(self):
+        return self._max_build_plate
+
+    def setActiveBuildPlate(self, nr):
+        self._active_build_plate = nr
+        self.activeBuildPlateChanged.emit()
+
+    @pyqtProperty(int, notify = activeBuildPlateChanged)
+    def activeBuildPlate(self):
+        return self._active_build_plate
+
+    def _updateSelectedObjectBuildPlateNumbers(self, *args):
+        result = set()
+        for node in Selection.getAllSelectedObjects():
+            result.add(node.callDecoration("getBuildPlateNumber"))
+        self._selection_build_plates = list(result)
+        self.selectionChanged.emit()
+
+    @pyqtProperty("QVariantList", notify = selectionChanged)
+    def selectionBuildPlates(self):
+        return self._selection_build_plates