Improve PopulateRelationship layout in Relation panel

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Improve PopulateRelationship layout in Relation panel. First, improve the 
relationship selector in the first subpanel by adding label and JXTable 
components, disable all subpanels is no relationship is selected. Improve the 
neighorconstraint subpanel due to the fact that its use is not clear, add an 
editable combobox with default selectable values in this combobox which 
represents the neighorconstraint value. In other condition subpanel, add a 
choice in the third combobox that open a popup that enable to make a comparison 
between the selected item in the first and second combobox. Add a button which 
enable the user to test if his or her relation correctly works.

Original issue reported on code.google.com by rybak.jonathan on 29 Jul 2013 at 7:28