Record the ranges tried so far, from several processes

[briandfoy]

When a process checks a range of numbers, record that somewhere. Let several processes do this. Let several processes read this to now what to do next.

The usenet article range stuff might be interesting here. And, maybe some redis. the .newsrc or Set::IntSpan will be interesting here.

[briandfoy]

The tools/checked_ranges figures this out, but the output files didn't note that they'd finished the range they were testing so there are holes at the end of every range. That's not a big deal since we can re-run the tail ranges again to make new output files. The excellent-gmp.c program was modified to print a progress statement at the end of its run.

[briandfoy]

The latest progress output notes the start and progress values at each checkpoint now, so that makes things easier. The tools/restart_run can no pick up where a run left off since it gets the last value and end value from the output file.