Fixing viewport shuffling due to image load

Introduced new method ".loadImages()" in posts client side lib
to handle viewport height changes when loading images. Requires
nodebb-plugin-markdown@5.0.0

@BenLubar @boomzillawtf

public/src/utils.js

@@ -309,6 +309,23 @@
 			return labels;
 		},
 
+		/* Retrieved from http://stackoverflow.com/a/7557433 @ 27 Mar 2016 */
+		isElementInViewport: function(el) {
+			//special bonus for those using jQuery
+			if (typeof jQuery === "function" && el instanceof jQuery) {
+				el = el[0];
+			}
+
+			var rect = el.getBoundingClientRect();
+
+			return (
+				rect.top >= 0 &&
+				rect.left >= 0 &&
+				rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && /*or $(window).height() */
+				rect.right <= (window.innerWidth || document.documentElement.clientWidth) /*or $(window).width() */
+			);
+		},
+
 		// get all the url params in a single key/value hash
 		params: function(options) {
 			var a, hash = {}, params;