Fix highlights for right-aligned bars.
Fix highlights for right-aligned bars.

Support for right-aligned bars was never added to the hover or highlight
code; only the actual bar drawing. We need to replicate that in the
other two places as well.

Resolves #1093.

chiu/flot,chaveiro/flot,mcanthony/flot,TrainingPeaks/flot,soenter/flot,resnick1223/flot,fashionsun/flot,sedran/flot,matong/flot,pepperdata/flot,soenter/flot,chiu/flot,klarkc/flot,lolifans/flot,mlitwiniuk/flot,saike/flot,chaveiro/flot,gdseller/flot,ni-kismet/engineering-flot,kongx73/flot,cipix2000/engineering-flot,flot/flot,magora-suchkov/flot,andig/flot,MAMISHO/flot,andig/flot,chaveiro/flot,mlitwiniuk/flot,k-joseph/flot,mlitwiniuk/flot,chiu/flot,octavianCraciun/engineering-flot,Sensirion/flot,k-joseph/flot,cipix2000/flot,stanislavdavid/flot,andig/flot,colinhunt/flot,resnick1223/flot,saike/flot,stanislavdavid/flot,stanislavdavid/flot,resnick1223/flot,cipix2000/flot,k-joseph/flot,saike/flot,petrvacha/flot