Allow using connector pin names to define connections

Pin names from pinout list can now be used in addition to pin numbers when defining connections, provided the identifier is unambiguous.
Closes #71.

src/wireviz/Harness.py

@@ -26,6 +26,30 @@ def loop(self, connector_name, from_pin, to_pin):
         self.connectors[connector_name].loop(from_pin, to_pin)
 
     def connect(self, from_name, from_pin, via_name, via_pin, to_name, to_pin):
+
+        for (name, pin) in zip([from_name, to_name], [from_pin, to_pin]): # check from and to connectors
+            if name is not None and name in self.connectors:
+                connector = self.connectors[name]
+                if pin in connector.pinnumbers and pin in connector.pinout:
+                    if connector.pinnumbers.index(pin) == connector.pinout.index(pin):
+                        # TODO: Maybe issue a warning? It's not worthy of an exception if it's unambiguous, but maybe risky?
+                        pass
+                    else:
+                        raise Exception(f'{name}:{pin} is defined both in pinout and pinnumbers, for different pins.')
+                if pin in connector.pinout:
+                    if connector.pinout.count(pin) > 1:
+                        raise Exception(f'{name}:{pin} is defined more than once.')
+                    else:
+                        index = connector.pinout.index(pin)
+                        pin = connector.pinnumbers[index] # map pin name to pin number
+                        if name == from_name:
+                            from_pin = pin
+                        if name == to_name:
+                            to_pin = pin
+                        # TODO: what happens with loops?
+                if not pin in connector.pinnumbers:
+                    raise Exception(f'{name}:{pin} not found.')
+
         self.cables[via_name].connect(from_name, from_pin, via_pin, to_name, to_pin)
         if from_name in self.connectors:
             self.connectors[from_name].activate_pin(from_pin)