Take account of refraction in optics

[SeanDS]

New layout manager? Or new methods in components to map inputs to outputs?

Maybe modify abstract component to provide methods:

• addInputOutput(blah, blah, inputPos=Coordinates(-0.5, 0), refractive_index = 1.45) - adds an input and calculates the corresponding output position (does this require symmetric components?)
• addInput(blah, blah, pos=Coordinates(...)) - just adds an input
• addOutput(blah, blah, pos=Coordinates(...)) - just adds an output