Added scrollToElement() method

src/scrollers/scrollToElement.ts

+import * as Velocity from 'velocity-animate';
+import {EASE_IN_SKIP_OUT_EASING} from '../easing/setupVelocity';
+
+export function scrollToElement(element: HTMLElement, onScrollFinishedCallback?: () => void): void
+{
+	Velocity.animate(element, 'scroll', {
+		duration: 1200, // todo: different depending on offset from page top?
+		easing: EASE_IN_SKIP_OUT_EASING,
+		complete: () => onScrollFinishedCallback !== undefined && onScrollFinishedCallback(),
+	});
+}