Is the base interface of the User Interface of a table header.
A table header is managed as a DOM element list, using the current table structure and renderer.
Current implementation does not use the data model and relays heavily on {@link org.itsnat.core.domutil.ElementList}.
@author Jose Maria Arranz Santamaria
@see ItsNatTableHeader#getItsNatTableHeaderUI()
@see ItsNatTableHeader#getItsNatTableHeaderCellRenderer()
@see org.itsnat.comp.table.ItsNatTable#getItsNatTableStructure()
@see org.itsnat.core.domutil.ElementList