changed: Implement pausable priority and get rid of old method
changed: Use CJob::PRIORITY_LOW_PAUSABLE for (non-essential) image jobs
changed: Pause low priority jobs when loading/showing pictures
changed: Rename pausedType to something more suitable
fixed: Music playlist wouldn't progress with pending jobs (fixes #14574)
Merge pull request #3194 from arnova/slow_picture_job_fix

changed: Pause low priority jobs when loading/showing pictures