Update Arabic translation
Refactored eog jobs system.
EogJobs: Fix signalling callbacks

Make sure the callbacks are only called once each time.
EogJobs: Make EogJobTransform work again

This re-uses the old job code and needs to be
extended with proper cancellation checks.
EogJobs: Make EogJobCopy work with the new scheduler

Also uses the old worker code for now until job cancellation
is fully implemented.
EogJobs: Reinstate EogJobSave and EogJobSaveAs

These are also missing cancellation for now.
EogImage: Allow calling image_load outside of EogJobs

This is still needed for the statusbar-date plugin.
EogImage needs to be aware of the load jobs to get this away.