run ;cmd through a shell

[StefanKarpinski]

I like this behavior a lot better – it behaves like your shell, which is really much nicer. If people like this, I think we should do it. There is a remaining issue with it, however, which is that there's no way to use shell variables.

[timholy]

Are there any performance implications? For example, the time it takes to start up the shell?

[StefanKarpinski]

It seems reasonably fast to me and since it's a strictly interactive feature, if it feels fast enough, it is fast enough.

[pao]

This appears like it will be horrifically broken on Windows.

[StefanKarpinski]

Ah, that's a good point. I guess on Windows since there's no shell, we can just skip this.

[StefanKarpinski]

This is so much nicer than the old behavior, I just have to merge this. Supporting shell variable interpolation strikes me as unimportant since any programming with variables should probably be done in Julia land instead.