Graphics code changes

# 1. Make Swing the new default Java graphics impl. Move former `graphics` to wolframite.tools.graphics-legacy-awt and turn `wolframite.tools.experimental` to `...graphics`. The advantage is that it uses a more modern (though also ancient) graphics library, and that more work is done by Wolfram provided code. It also uses a global var 🙀 so that you only need a single function, `show!`, without any extra setup. Cons: 1. We only support a single window currently (could be changed) 2. We don't implement scaling of the content, as the AWT version did; again, we could do it, if requested # 2. Rename `view` fns to `show` for consistency with the java version and with Wolfram having a Show function. # 3. graphics/show! supports multiple windows/visualizations Modify graphics/show! to take an optional `window` argument, so that you can force it to create a new window, e.g. to display two graphs next to each other for comparison.