Some run-all.ps1 changes

[tomjaguarpaw]

We should merge something like https://github.com/awf/autodiff/tree/toelli/run-all. The commit that unredirects stderr should be tidied up a bit.

[tomjaguarpaw]

Perhaps we can capture stderr, add the indent, and output it immediately. I'm not sure how to do that in Powershell.

[awf]

Oddly it's 2>file, e.g. & {write-host "una"; "conor"; write-error "fed"} 2>err.txt >out.txt