fix: misplacement of current time indicator (jquense#1239)

Hello,
It looked like PR for this issue (jquense#1054) was abandoned and the bug still exists so I've decided to continue jdaberkow's work.
Also I've added check for `getNow` prop, because when you want to implement timezones you may have different `getNow` function depending on which timezone is selected. When user changes the timezone indicator should move to correct position for that timezone.

src/DayColumn.js

@@ -44,13 +44,22 @@ class DayColumn extends React.Component {
   }
 
   componentDidUpdate(prevProps, prevState) {
-    if (prevProps.isNow !== this.props.isNow) {
+    const getNowChanged = !dates.eq(
+      prevProps.getNow(),
+      this.props.getNow(),
+      'minutes'
+    )
+
+    if (prevProps.isNow !== this.props.isNow || getNowChanged) {
       this.clearTimeIndicatorInterval()
 
       if (this.props.isNow) {
-        this.setTimeIndicatorPositionUpdateInterval(
+        const tail =
+          !getNowChanged &&
+          dates.eq(prevProps.date, this.props.date, 'minutes') &&
           prevState.timeIndicatorPosition === this.state.timeIndicatorPosition
-        )
+
+        this.setTimeIndicatorPositionUpdateInterval(tail)
       }
     }
   }