Idea: run multiple independent pipelines simulataneously

[nh13]

For example, we could have an dagr option that specifies a file in which there are multiple pipeline-and-arguments specified (say one-per-line, or colon delimited (removing whitespaces and end-of line backslashes?)). I have many cases where I want to run the same pipeline N ways but with different options, yet I don't want to write a new "aggregate" pipeline (etc.). Seems like this would be easy and convenient. We could even have a "watch directory" where new "dagr" scripts are put and loaded by "dagr". Perhaps that's a separate tool.