Use Positive modifier instead of combining NonZero and NonNegative.
Use mapSize from QuickCheck instead of making our own version.
Merge branch 'nick8325-master'
Use Positive modifier instead of combining NonZero and NonNegative.

(cherry picked from f756587261a2428de9fe23d30591734604b26f48)
Use mapSize from QuickCheck instead of making our own version.

(cherry picked from 1535364e9635bc318e235824e92e973604b172ab)
Merge branch 'maint-2.4.0'