Don't update color palette when Selector tool is picked

This makes it possible e.g to use the colorPicker app in conjunction
with the compass.
Colors will still be updated when one clicks the pen or marker tools.

src/board/UBDrawingController.cpp

@@ -147,7 +147,8 @@ void UBDrawingController::setStylusTool(int tool)
             UBApplication::mainWindow->actionCapture->setChecked(true);
 
         emit stylusToolChanged(tool);
-        emit colorPaletteChanged();
+        if (mStylusTool != UBStylusTool::Selector)
+            emit colorPaletteChanged();
     }
 }