Improve CLI

[Badel2]

The command line interface should be a replacement to the web interface, especially useful with the Stdin and Stdout components. There should be an interactive mode and a bash mode. The interactive mode would ideally be a ncurses-based interface, and the bash mode will just run the simulation and output the results.

An alternative to the ncurses interface would be a real GUI, but we could just bundle the web demo and call that a GUI.

Some starting points:

• Basic ncurses interface (see cursive crate)
• Interactive input setting
• Interactive pause/step/resume
• A basic signal viewer
• Ability to monitor specified signals
• Ability to record state and go back in time
• Integration with netlistsvg to render components to a file
• Integration with netlistsvg to render the live state of a component (similar to the web demo)
• Test framework: run component and verify output
• Use the test framework in travis
• Parse arguments with clap