Changed, Thing Edit Form: floor slopes are now taken into account when changing thing's absolute Z position (currently, only slopes, created using sector planes, vertex height offsets and "Plane_Align" (181) action are supported).
Changed, Thing Info panel: floor slopes are now taken into account when showing thing's Z position (same plane type limitations as above).
Changed, Thing Info panel: thing position is now shown as "X, Y, Z (abs. Z)".