title: Leaflet zoom direction with javascript events
body: <p>I need functionality to check in what direction is map scrolled. 
  I show some text on a map using tooltips and need to change font-size depending on zoom level.</p>
  
  <p>I had tried with <strong><code>'wheel'</code></strong> event but it is fired only out of a Map.
  Also as I know there is no direction event on <strong><code>'zoomstart'</code></strong> and <strong>'zoomend'</strong> events.</p>
  
  <p>I know that checking zoom direction is not Leaflet's by the book way but any suggestion or solution will help me a lot. </p>