reinsert navigation direction bug fix for 10.10 also for arrow keys, because the scroll direction is still wrong on 10.10.5
reinsert navigation direction bug fix for 10.10 also for arrow keys, because the scroll direction is still wrong on 10.10.5

JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim