Buffering shell output

[ruricolist]

Like any tool that runs shell commands in parallel, Overlord is faced with the problem of interleaving the output from different commands. I'd like to find a solution that is (1) principled -- not just a mess of options for different output styles; that (2) solves the problem on the OS side, rather than by using Gray streams; and that (3) never leaves the user wondering whether the build is hanging.

Of course it may be that no solution satisfies all these constraints.