Fix double-add of flags to linked flags list if flags make up a circle with an even number of elements >2. This would cause an error message somewhere in the power system.

e.g.:
for (var a=0; a<360; a+=360/18) CreateObject(WindGenerator,Sin(a,450)+500,Cos(a,450)+500,player);

The algorithm is still weird. Why are three lists needed to traverse the graph of connected flags?