Added Parallel Layout Button. This was for testing how Parallel Layout worked, I'm pretty much done with it now.
Unimportant update. Just added the code that adds the listener to parallel layout button.
Parallel edges don't overlap each other anymore, now they run seperately but alongside each other. This was done by rendering Parallel layout after rendering the current layout, then setting it back to the current layout without rendering. Also made stakeholders with no relations loosely follow the stack layout. This way no matter what layout the tester chooses, the vertices should never pile on top of each other because they have no edges.