Add semaphore for high-memory areas

[choosehappy]

For example, some modules may operate at a higher magnification limiting parallel processing.

Limiting the # of processes executing within that module would be nice

Seems to be possible by adding a high memory option in the base config, creating a semaphore and then modifying the worker launch similar to like:

            if process_params["high_mem"]:
                with semaphore:
                    process(s, process_params)
            else:
                process(s, process_params)