Add job progress monitoring

[adamkewley]

Some developers are in the lucky position of knowing roughly how far their jobs have progressed. It would be useful if Jobson could "understand" that, in a clean way.

Suggested ideas:

• Child process sets an environment variable (e.g. PROGRESS) to a decimal value for the progress
• Child process writes progress in a parsable from to an output pipe (e.g. stdout). Jobson recognizes the pattern, and uses it to calculate progress
• Child process writes progress to a file, which Jobson polls
• Others: message queue, semaphore, shared memory, etc.

[adamkewley]

This link gives all that's possible: http://www.tldp.org/LDP/lpg/node7.html

[adamkewley]

This has been kicked back to post-1.0.0