Improve fix wrong code generation if EN/ENO are used in FBD/LD/SFC

Commit c9915bc6 "Fix wrong code generation if EN/ENO are used in
FBD/LD/SFC" caused following backtrace in some cases:

File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 476, in GenerateProgram
self.GeneratePouProgram(pou_name)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 258, in GeneratePouProgram
program = pou_program.GenerateProgram(pou)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1713, in GenerateProgram
self.ComputeProgram(pou)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 997, in ComputeProgram
eno_var = self.GetUsedEno(body, connections)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 929, in GetUsedEno
for invar in blk.inputVariables.getvariable():
File "/home/developer/WorkData/PLC/beremiz/beremiz/xmlclass/xmlclass.py", line 1363, in getattrMethod
return DefaultElementClass.__getattribute__(self, name)
<type 'exceptions.AttributeError'>: 'inOutVariable' object has no attribute 'inputVariables'

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// import Nevow.Athena

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function init() {

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  Nevow.Athena.Widget.fromAthenaID(1).callRemote('HMIexec', 'HMIinitialisation');

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}

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WebInterface.PLC = Nevow.Athena.Widget.subclass('WebInterface.PLC');

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WebInterface.PLC.method(

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	 'updateHMI',

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	 function (self, data) {

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	   d = self.callRemote('getPLCElement');

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	   d.addCallback(

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			 function liveElementReceived(le) {

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				d2 = self.addChildWidgetFromWidgetInfo(le);

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				d2.addCallback(

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						function childAdded(widget) {

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						var node = self.nodeById('content');

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						node.replaceChild(widget.node, node.getElementsByTagName('div')[0]);

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						init();

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						});

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				});

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	   });

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Divmod.Base.addLoadEvent(init);