Fix more NaNs in Elastic Nodes example
Fix more NaNs in Elastic Nodes example

Don't try to draw zero-length lines. Don't draw lines if nodes are
superimposed.

Reviewed-by: Andreas

igor-sfdc/qt-wk,KDE/qt,RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,KDE/qt,radekp/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,KDE/qt,RLovelett/qt,RLovelett/qt,radekp/qt,radekp/qt,igor-sfdc/qt-wk,KDE/qt,pruiz/wkhtmltopdf-qt,radekp/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,radekp/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,KDE/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,KDE/qt,pruiz/wkhtmltopdf-qt,radekp/qt,radekp/qt,pruiz/wkhtmltopdf-qt,radekp/qt,radekp/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,radekp/qt,KDE/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt,RLovelett/qt,KDE/qt