auto-adjust wires when inverting inputs

[dfbg]

When inverting inputs to Logic symbols the inverting circle appears but the wire endpoints stay at the uninverted position and are subsequently disconnected. The wires should adjust to stay connected.

It might require checking that it won't accidentally cause to wires to connect. But hopefully there aren't many circuits being created with such crowding.

[hneemann]

Up to now there is no functionality implemented which moves wires programmatically. Wires are always moved by the user. Adding such a feature needs a bit more thinking about how to implement such a feature. I'm not sure if it is worth the effort.

See also #6