CLPExpression.add(CLPExpression)

[loehndorf]

It would be useful to have something like

CLP model = new CLP();
CLPVariable var1 = model.addVariable(), var2 = model.addVariable(), var3 = model.addVariable();
CLPExpression e1 = model.createExpression();
e1.add(var1);
CLPExpression e2 = model.createExpression();
e2.add(var2).add(var3);
e1.add(e2).leq(4);