Addition of the shift icon in the toolbar.
Creating the panel for shifting instances.
Improving the presentation.
Use the snap properties of the room for filling the text fields.
Implementing the shift.
Use message properties for displaying labels and title.
Adding the undo for shifting.
Adding more tests.
Undo : always select the piece in the list before moving it.
Modifying the titles of the dialog window.
Adding the clear button.
Clearing instances.
Changing message.
Reset the undo when instances/tiles are deleted.
Updating messages.
Select each instance/tile when shifting, otherwise the instances/tiles
are sometimes not correctly selected.
Changing messages.
Merge pull request #131 from egofree71/master

Adding global shifting and delete of instances and tiles.