Merge branch 'master' of github.com:ultimaker/Cura into feature_material_editing

* 'master' of github.com:ultimaker/Cura: (38 commits)
  Fixed profile file case-sensitivity.
  Fix UMO Checkup button size
  Remove debug statement and commented-out code CURA-1385
  Show "ready" state when a printer is connected but jobstate is not yet set
  Added deepcopy function
  Made exception handling of slice info plugin way more robust
  Restart timer after slicing is performed when not enabled.
  Update GUID for PLA to match the GUID in the official repository
  Set default extruder index to -1 (so global is default)
  Ensure that the display matches with the backend active extruder data
  Update UM2 Extended build volume height to value published in marketing materials
  Fixed firmware upgrade for um2+
  Capitalise setting label
  CHeckup action now correctly resets every time you start it
  Remove unused name/id when importing a profile from a gcode file
  Just a little typo
  BQ Hephestos2: Heat up nozzle while leveling
  Saving g-code no longer crashes
  Removed update firmware from extensions; This is now handled by machine actions
  Changing active extruder no longer trigger re-slice
  ...

cura/Settings/ExtruderManager.py

@@ -22,7 +22,7 @@ class ExtruderManager(QObject):
     def __init__(self, parent = None):
         super().__init__(parent)
         self._extruder_trains = { } #Per machine, a dictionary of extruder container stack IDs.
-        self._active_extruder_index = 0
+        self._active_extruder_index = -1
         UM.Application.getInstance().globalContainerStackChanged.connect(self._addCurrentMachineExtruders)
 
     ##  Gets the unique identifier of the currently active extruder stack.
@@ -66,6 +66,10 @@ class ExtruderManager(QObject):
         self._active_extruder_index = index
         self.activeExtruderChanged.emit()
 
+    @pyqtProperty(int, notify = activeExtruderChanged)
+    def activeExtruderIndex(self):
+        return self._active_extruder_index
+
     def getActiveExtruderStack(self):
         global_container_stack = UM.Application.getInstance().getGlobalContainerStack()
         if global_container_stack: