Adds layer count

Brings back the layer count, the min & max. And it does not display these untill Cura is done slicing.

Fixes #117

plugins/LayerView/LayerView.py

@@ -27,9 +27,13 @@ class LayerView(View):
         self._max_layers = 10
         self._current_layer_num = 10
         self._current_layer_mesh = None
+        self._activity = False
 
         self._solid_layers = 5
 
+    def getActivity(self):
+        return self._activity
+
     def getCurrentLayer(self):
         return self._current_layer_num
     
@@ -114,13 +118,14 @@ class LayerView(View):
 
             self._current_layer_mesh = None
             self.currentLayerNumChanged.emit()
-    
+
     currentLayerNumChanged = Signal()
-    
+
     def calculateMaxLayers(self):
         scene = self.getController().getScene()
         renderer = self.getRenderer()
         if renderer and self._material:
+            self._activity = True
             renderer.setRenderSelection(False)
             self._old_max_layers = self._max_layers
             ## Recalculate num max layers
@@ -138,10 +143,11 @@ class LayerView(View):
             if new_max_layers > 0 and new_max_layers != self._old_max_layers:
                 self._max_layers = new_max_layers
                 self.maxLayersChanged.emit()
+                self._current_layer_num = self._max_layers
 
                 # This makes sure we update the current layer
                 self.setLayer(int(self._max_layers * (self._current_layer_num / self._old_max_layers)))
-    
+
     maxLayersChanged = Signal()
     
     ##  Hackish way to ensure the proxy is already created, which ensures that the layerview.qml is already created