Fix document name display in Nuxeo Shell

A document whose name starts with a dot will be incompletely display in Nuxeo Shell.

Administrator@localhost:/> mkdir Folder .testing
Administrator@localhost:/> ls
/.testin
Administrator@localhost:/> rm /.testin
org.nuxeo.ecm.automation.client.RemoteException: Failed to execute operation: Document.Delete

There is a problem to get the last segment of a path, which is used as the document name. Actually, when the segment starts with a dot, the offset is not correctly set : it is reset like if it was a slash, whereas it should be incremented like for any other character.