Complete 2D and 3D viewing features

Full test of (almost all) 2D and 3D features:

• Viewing results in 2D mode works acceptably now (results are shown in orthographic mode).
• Overlay and side-by-side view can be toggled through an item in the View menu.
• More fixes for the mac code signing situation. Please unzip the binary and then move Athena.app to some other directory to avoid crashes at startup time. (I know, it's weird. I'm hoping to improve this in the future.)