Move layers button in Layers view not working with multiple selection about udig-platform

[fgdrf]

Multible layers in selection makes the command at the end obsolete. E.g. if you have 3 layers ['1', '2', '3'] and select '1' and '2' the expectation is that at the end it looks like this : ['3', '1', '2']

What happens: For each layer beginning with '1' a moveDown Command is called. After '1' is moved the same command is called for layer '2' and the current ordering of ['2', '1', '3'] which results into ['1', '2', '3']

[fgdrf]

see pull request #241

[fgdrf]

Tested with Multible selection where object are not selected in between ▶️