Prevent some nodes from disappearing from the graph

There's a filter in place to not show nodes not connected to any other
node, however the strict inequality was also filtering out nodes
connected to exactly one other node.

src/Gargantext/Core/Viz/Graph/Tools.hs

@@ -218,8 +218,8 @@ data2graph multi labels' occurences bridge conf partitions =
             | (label, n) <- labels
             , Set.member n toKeep
             ]
-
-    (bridge', toKeep) = nodesFilter (\v -> v > 1) bridge
+    -- Filter out nodes not connected to any other node
+    (bridge', toKeep) = nodesFilter (\v -> v >= 1) bridge
 
     edges = [ Edge { edge_source = show s
                    , edge_hidden = Nothing