Save/Restore session

Something that would be useful to have is a save/restore functionality, where previous entered code and state can be restored in a future session.

1. User enters trymodule lodash and repl opens with lodash installed
2. User enters var something = lodash.repeat('WIN', 5)
3. User enters save()
4. User closes repl and opens it again with trymodule colors
5. User enters restore()

And now something and lodash is available in the repl again.