1) In response to issue 4263, try a little harder to produce nice scales

when there is scope to do so.

2) When chart is type 'bar', ensure reference to zero is maintained
when zoomed and auto scaling the Y axis.

src/modules/Scales.js

@@ -267,6 +267,11 @@ export default class Scales {
         } else {
           let yMaxPrev = yMax
           yMax = stepSize * Math.ceil(yMax / stepSize)
+          if (Math.abs(yMax - yMin) / Utils.getGCD(range, stepSize) > maxTicks) {
+            // Use default ticks to compute yMax then shrinkwrap
+            yMax = yMin + stepSize * ticks
+            yMax -= stepSize * Math.floor((yMax - yMaxPrev) / stepSize)
+          }
         }
       }
       range = Math.abs(yMax - yMin)