Previously, if a project specified a limit on GPU jobs in progress,
it would be enforced across GPU types.
This could lead to starvation for hosts with multiple GPU types.
E.g. the limit is 10, and a host has 10 NVIDIA jobs and no AMD jobs.
Fix this by enforcing limits separately for each GPU type.
You can now specify limits for specific apps,
and/or for the project as a whole.
Within each of these, you can specify limits on
CPU jobs, GPU jobs, or total jobs.
In the case of CPU and GPU limits, you can specify
whether the limit should be scaled by the number of devices.
Note: the enforcement of this is done in get_app_version(),
since per-resource-type limits may dictate what app versions
we can use for a particular job.
svn path=/trunk/boinc/; revision=21674
David Anderson