Interactive stdout & stop button

[gjz010]

For computations that need a long time (e.g. GPU acceleration case), the user may expect to see output as long as they are printed, rather than after all computation tasks have completed.

Also, since the computation is in WebWorker now, a button for killing the program in execution would be favoured, e.g. using Worker.terminate()

[imtsuki]

Currently all outputs are stored in an array and only sent back after the whole execution is done. Yes, we should use something like posting messages or a shared buffer to get real-time outputs.

[AGDholo]

• stop button feat: stop web worker & prefetch and loading script via url parameter & add lint rules #71

• Interactive stdout