Stepper: Import statements cause errors

[leeyi45]

Running any code with an import statement in the stepper simply produces the output error

[martin-henz]

Instead of an error, the stepper should accommodate imported modules and display values created by modules in appropriate ways. For example, runes should be displayed within steps of the stepper:

import { heart, quarter_turn_left, show } from "rune"; show(quarter_turn_left(heart));
=>
show(quarter_turn_left(■));
=>
show(■);
=>
■;

In this case, the stepper would use the ■ symbol to represent any rune.

Of course even better would be to display a mini-version of the actual rune in the stepper:

import { heart, stack, show, red } from "rune"; show(quarter_turn_left(heart));
=>
show(quarter_turn_left(♥));
=>
show(❥);
=>
❥;

[martin-henz]

In addition, every evaluation of "show" should lead to a display of the rune in the runes tab. This is already working in the environment visualizer.