VORONOi: lien pays adaptable

When $COUNTRY role is supplier, the link display is between supplier from $COUNTRY and requesting from other country. 

When $COUNTRY role is requesting, the link display is between requesting from $COUNTRY and supplier from other country. 

The national links from $COUNTRY to $COUNTRY aren't display. 

Only the top 15 country are display the others are group in two category : $OTHER_IN_REGION and $OTHER_NOT_IN_REGION