feat: add missing duration setting

BREAKING CHANGE: The option slideSpeed has been renamed to duration. Also, the default value for duration is
now 300ms, instead of 200ms.

docs/new.html

@@ -71,7 +71,7 @@ <h1>
     panelSelector: '> section',
     directionThreshold: 50,
     delay: 0,
-    slideSpeed: 200,
+    duration: 300,
     easing: function(t) { return t },
   };
 
@@ -90,7 +90,7 @@ <h1>Options explained</h1>
         <dd>(interger) The amount of pixels required to scroll before the plugin detects a direction and snaps to the next panel.</dd>
         <dt>delay</dt>
         <dd>(integer) The amount of miliseconds the plugin pauzes before snapping to a panel.</dd>
-        <dt>slideSpeed</dt>
+        <dt>duration</dt>
         <dd>(integer) The amount of miliseconds in which the plugin snaps to the desired panel.</dd>
         <dt>easing</dt>
         <dd>(function) An easing function specificing the snapping motion.</dd>

src/panelSnap.js

@@ -17,7 +17,7 @@ const defaultOptions = {
   panelSelector: '> section',
   directionThreshold: 50,
   delay: 0,
-  slideSpeed: 200,
+  duration: 300,
   easing: t => t,
 };
 
@@ -176,12 +176,14 @@ export default class PanelSnap {
 
     this.targetScrollOffset = getTargetScrollOffset(this.container, panel, toBottom, toRight);
 
-    const start = 0;
-    const end = TWEEN_MAX_VALUE;
-    const duration = 300;
+    this.animation = new Tweezer({
+      start: 0,
+      end: TWEEN_MAX_VALUE,
+      duration: this.options.duration,
+    });
 
-    this.animation = new Tweezer({ start, end, duration });
     this.animation.on('tick', this.animationTick.bind(this));
+
     this.animation.on('done', () => {
       this.emit('snapStop', panel);
       this.clearAnimation();