Quit early when no jobtypes supported
Don't look only at running jobs in scheduler

Still prefer them to queued jobs, if they are at the same priority.

This will make the scheduler start newly queued jobs with a higher
priority immediately instead of waiting to run out of running jobs in
the current queue.
Assume not-running jobs have 0 agents assigned

This is an optimization; without it, the scheduler would run too long
now that it is also considering queued jobs by default.
Fix typo: remove "not"
Fix access to undefined local variable
Don't run jobs with unmet dependencies
Fix sorting objects for assignment by weight
Ignore not-started jobs when getting weight_sum

Assignment by weight is only supposed to apply to already active jobs
anyway.
Bugfix: Explicitly convert values to float

On Python 3, int/int will automatically be converted to float if
necessary.  On Python 2, however, it won't, and will just discard the
fractional parts of the result.

This bug led proportional agent assignments by object weight not working
right.
Merge pull request #314 from guidow/fix_scheduler_minimums_and_prios

Fix scheduler minimums and prios