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In order to allow informed decissions on when to start a job,
it is necessary for luxid to keep track of the (active part
of the) job queue. Add a scheduler, similar to the config reader,
that does this, but also schedules jobs to be executed. At the
moment this is just the simple mechanism of starting jobs until
a fixed number of running jobs is reached.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>