• paired single primes ( ' ' ) become single quotes ( ‘ ’ )
• lone single primes become apostrophes ( ’ )
• paired double primes ( " " ) become double quotes ( “ ” )
• a double dash ( -- ) becomes an em dash ( — )
• a single dash ( - ) become an en dash ( – )
• *emphasized text* becomes strong text

try me:
nils’ “smart quote” replacement modification of David Lindquist’s script.