add pipes; add async and iterative maps

[mmckerns]

needs async and blocking pipes, and upon that can build async and iterative maps

[mmckerns]

async map should be "easy", just don't block on the appearance of the results file. iterative maps are a bit nastier. Iterative is more difficult because the scheduler file is returned only when the job is finished -- so there seem to be two routes to implement this: (1) add some form of wrapper to print to stdout or a file and then capture the output and send it back to the caller, or (2) split the map into several smaller jobs (inside a job 'reservation' block) and catch the job files as they come back.

[fzimmermann89]

Hi, is there any progress on adding async map?

[mmckerns]

@fzimmermann89: Unfortunately, not yet. I keep meaning to get to this issue, but it keeps getting bumped.