Use multiprocessing.Pool for parallel I/O
This PR modifies gwpy.io.mp.read_multi
to use multiprocessing.Pool
(instead of ProcessQueue
) for parallel file reading, enabling trivial parallel I/O for astropy registered readers (e.g. ASCII). Files are now passed through the pool one-by-one, so readers in gwpy.table.io
only need to be built to handle a single file at a time.