#6 Remove "button-pressing" threads

[jeff yoshimi]

All the threads currently press buttons by invoking a
JButton method. This should be changed. Note the
following email from Jason Laurel:
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I noticed in your network panel that when you press
the "play" button you are basically pressing the "step"
button continuously. Unless you prefer the
flickering "step" button, why don't you just call the
code that the step button normally invokes. For
example, in your NetworkThread class, do this:

//panelRef.stepBtn.doClick();
panelRef.updateNetwork()

You can play around with things like changing the
button color to indicate it's pressed, or you can use a
JToggleButton instead of a regular JButton..