make nodes and lines hashable again

src/kyupy/circuit.py

@@ -101,9 +101,14 @@ class Node:
 
     def __eq__(self, other):
         """Checks equality of node name and kind. Does not check pin connections.
+
+        This is ok, because (name, kind) is unique within a circuit.
         """
         return self.name == other.name and self.kind == other.kind
 
+    def __hash__(self):
+        return hash((self.name, self.kind))
+
 
 class Line:
     """A line is a directional 1:1 connection between two nodes.
@@ -181,6 +186,9 @@ class Line:
         return self.driver == other.driver and self.driver_pin == other.driver_pin and \
                self.reader == other.reader and self.reader_pin == other.reader_pin
 
+    def __hash__(self):
+        return hash((self.driver, self.driver_pin, self.reader, self.reader_pin))
+
 
 class Circuit:
     """A Circuit is a container for interconnected nodes and lines.