Rewritten exportCellVarsAs in a more compact and clear form - should be easier to integrate with export of composite elements
Rewritten exportIntVarAs, exportPrimVarAs and added getNodalVariableFromIS in analogy with getPrimaryVariable
Merge branch 'VTKExport' of github.com:JimBrouzoulis/OOFEM_Jim

Conflicts:
	src/oofemlib/vtkxmlexportmodule.C
Some small updates in the vtkxmlexport module