Finds further path nodes within the cone of the last path_scan instruction.
ENTITY* - entity pointer.
index - distance index, 0 == closest, 1 == second closest and so on.
The number of the node found,
or 0 if no more nodes were in the scan
ENTITY* - is attached to the path belonging to the found node.
result = path_scan(me,my.x,my.pan,vector(360,180,1000);
temp = path_scannode(my, 1); // get the next scanned path node