corrected HITS calculation (issue #620)

- initialized authority and hubs to 1 at each iteration
- used outgoing edges instead of incoming edges for hubs computation
- renamed 'target' to source for incoming edges in authority computation

Review of the logic would be appreciated.

Normalization is different from the one in the original paper, but this might not be affecting the logic. networkx uses same normalization logic as the one used here.

modules/StatisticsPlugin/src/main/java/org/gephi/statistics/plugin/Hits.java

@@ -170,17 +170,17 @@ public void execute(HierarchicalGraph hgraph, AttributeModel attributeModel) {
             for (Node node : auth_list) {
 
                 int n_index = indicies.get(node);
-                temp_authority[n_index] = authority[n_index];
+                temp_authority[n_index] = 1.0f;
                 EdgeIterable edge_iter;
                 if (!useUndirected) {
                     edge_iter = ((HierarchicalDirectedGraph) hgraph).getInEdgesAndMetaInEdges(node);
                 } else {
                     edge_iter = ((HierarchicalUndirectedGraph) hgraph).getEdgesAndMetaEdges(node);
                 }
                 for (Edge edge : edge_iter) {
-                    Node target = hgraph.getOpposite(node, edge);
-                    int target_index = indicies.get(target);
-                    temp_authority[n_index] += hubs[target_index];
+                    Node source = hgraph.getOpposite(node, edge);
+                    int source_index = indicies.get(source);
+                    temp_authority[n_index] += hubs[source_index];
                 }
 
                 auth_sum += temp_authority[n_index];
@@ -194,10 +194,10 @@ public void execute(HierarchicalGraph hgraph, AttributeModel attributeModel) {
             for (Node node : hub_list) {
 
                 int n_index = indicies.get(node);
-                temp_hubs[n_index] = hubs[n_index];
+                temp_hubs[n_index] = 1.0f;
                 EdgeIterable edge_iter;
                 if (!useUndirected) {
-                    edge_iter = ((HierarchicalDirectedGraph) hgraph).getInEdgesAndMetaInEdges(node);
+                    edge_iter = ((HierarchicalDirectedGraph) hgraph).getOutEdgesAndMetaOutEdges(node);
                 } else {
                     edge_iter = ((HierarchicalUndirectedGraph) hgraph).getEdgesAndMetaEdges(node);
                 }