Fixed #23992 -- Optimized reorder_suite functions using OrderedSet
Fixed timesince translations for Korean

Refs #23989.
Forward port of eb632bfba from stable/1.7.x.
Merge pull request #3730 from tchaumeny/test_suite_reorder

Fixed #23992 -- Optimized reorder_suite functions using OrderedSet
Fixed #23991 -- Apparently, Oracle doesn't need the decimal field converter

Thanks Josh Smeaton for review.
Fixed #16501 -- Added a unicode parameter to models.SlugField and forms.SlugField.