Network: Add edge add and del command.

src/Model/Network/Graph.py

@@ -103,10 +103,29 @@ class Graph(object):
     def insert_node(self, node):
         return self._add_node(node)
 
+    def remove_node(self, node_name:str):
+        self._nodes = list(
+            filter(
+                lambda n: n.name != node_name,
+                self._nodes
+            )
+        )
+        self._status.modified()
+
     def create_node(self, x:float = 0.0, y:float = 0.0):
         node = self._create_node(x, y)
         return node
 
+    def _create_edge(self, n1:Node, n2:Node):
+        edge = self._edge_ctor(
+            self._edges_ids,
+            "", n1, n2,
+            status = self._status
+        )
+        self._edges_ids += 1
+        return edge
+
+
     def _add_edge(self, edge):
         # This edge already exists ?
         if any(filter(lambda e: (e.node1 == edge.node1 and
@@ -115,28 +134,19 @@ class Graph(object):
             return None
 
         self._edges.append(edge)
-        self._edges_ids += 1
 
         self._status.modified()
         return edge
 
     def add_edge(self, n1:Node, n2:Node):
-        edge = self._edge_ctor(self._edges_ids,
-                               "", n1, n2,
-                               status = self._status)
+        edge = self._create_edge(n1, n2)
         return self._add_edge(edge)
 
     def insert_edge(self, edge):
         return self._add_edge(edge)
 
-    def remove_node(self, node_name:str):
-        self._nodes = list(
-            filter(
-                lambda n: n.name != node_name,
-                self._nodes
-            )
-        )
-        self._status.modified()
+    def create_edge(self, n1:Node, n2:Node):
+        return self._create_edge(n1, n2)
 
     def remove_edge(self, edge_name:str):
         self._edges = list(