Fixed bug where removeFileIfExists wouldn't catch the does-not-exist exception
Changed infoM to noticeM;  removed (now unused) infoM from the module.
Now the "Activating worker…" message no longer has the workload.
Decided that my NOTICE level messages are really only INFO level messages.
Now a problem writing the checkpoint causes an ERROR and a fix causes a NOTICE
Tweaked the descriptions of the checkpoint options.
Deleted extraneous space.
Now the delay occurs after the checkpoint is written rather than before.

This change was made because it means that if there is a
problem with writing the checkpoint it will be discovered
and reported immediately.
Added more meat to the checkpoint error message.
Added a feature that allows one to write regular "ticks" to a file.

This can be used to compute the amount of computational
resources used during a run which might start and be
resumed at various times.
Revert "Added a feature that allows one to write regular "ticks" to a file."

I realized that the implementation is not doing
the right thing because the ticks are not in sync
with the checkpoint.

This reverts commit a0c82a5a3c118466d8ec6493e1ab11aa55556397.
Added a mechanism for watching the number of workers.