gesture,internal/fling: fix rounding

The code tried to extract a rounded whole number of pixels while preserving the
fraction. However, it failed to converge for the value 0.5, rounded to 1,
leaving -0.5, rounded to -1, leaving 0.5 and so on.

Drop the cleverness and truncate the values instead.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

gesture/gesture.go

@@ -205,7 +205,7 @@ func (s *Scroll) Scroll(cfg unit.Converter, q event.Queue, t time.Time, axis Axi
 			case Vertical:
 				s.scroll += e.Scroll.Y
 			}
-			iscroll := int(math.Round(float64(s.scroll)))
+			iscroll := int(s.scroll)
 			s.scroll -= float32(iscroll)
 			total += iscroll
 			if !s.dragging || s.pid != e.PointerID {

internal/fling/animation.go

@@ -85,7 +85,7 @@ func (f *Animation) Tick(now time.Time) int {
 	ekt := float32(math.Exp(float64(k) * t.Seconds()))
 	x := f.v0*ekt/k - f.v0/k
 	dist := x - f.x
-	idist := int(math.Round(float64(dist)))
+	idist := int(dist)
 	f.x += float32(idist)
 	// Solving for the velocity x'(t) gives us
 	//