PR# 11042 Please add a "no wait" option to External Commands

The improvements to External Commands seem to be working well, but I do have one issue.

When a command is run now, I cannot execute a second command until the first one finishes. This is often inappropriate, e.g., if the external command starts a GUI rather than a command-line application.

I've found that an easy fix for this, on Windows at least, is to prefix the command with "start".

I figured this out easily, since I've had plenty of practice with this sort of thing, but I suspect this might cause a few people more trouble.

It would be nicer if you had an explicit "no wait" check box.