Add multiple queues w/ per queue job limits

[Rob Donnelly]

Add queues to help with resource (e.g. licenses) management. There would be both a per queue job limit and the pre-existing global job limit --max-jobs.

Example queue configuration:

• global limit is a function of CPUs
• compile queue - does not require a license, no limit
• short - requires a license, but only for short period, limit is a function of licenses
• long - requires a license for a long period of time, limit to a single job