[DRAFT] - Add copy command

[Prajjwal]

Closes #753

[st0012]

I think we need to apply the output inspection method here so the copied output will be closer to what the users may expect.

For example, the output here by default will be the to_s result of the evaluation result, but IRB's default output inspector pretty prints the result inspect.

Additionally, we need to make sure colorizing is NOT applied to the copied value.

[Prajjwal]

The problem with using the pretty printer is that colorizing output is hardcoded into it, and I don't think we want it in our clipboard.

Unless there's a pretty printer that I've missed, the options are:

1. Grab colorized output, strip color before copying. Least invasive, and will respect the currently configured inspector.
2. Install a new pretty printer analogous to the default color printer that does basically the same thing but doesn't colorize output. Don't like this one because we're conflating two concepts and hardcoding a command to use a specific kind of inspection method.
3. Like above, color_printer.rb to accept a parameter that turns colorizing on / off. Most invasive.

I like 1, but will defer.