Swapped out Packery for MagicGrid

This switches the Gallery shortcode to use MagicGrid instead of Packery.
The main benefit is size (2.7k as opposed to 32k), and the results are
mostly similar minus a few differences in image position.

assets/lib/magic-grid/magic-grid.min.js

@@ -0,0 +1 @@
+!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):t.MagicGrid=e()}(this,function(){"use strict";var t=function(t){if(!t)throw new Error("No config object has been provided.");"boolean"!=typeof t.useTransform&&(t.useTransform=!0),"number"!=typeof t.gutter&&(t.gutter=25),t.container||e("container"),t.items||t.static||e("items or static")},e=function(t){throw new Error("Missing property '"+t+"' in MagicGrid config")},i=function(t){var e=t[0];for(var i of t)i.height<e.height&&(e=i);return e},n=function(e){t(e),e.container instanceof HTMLElement?(this.container=e.container,this.containerClass=e.container.className):(this.containerClass=e.container,this.container=document.querySelector(e.container)),this.items=this.container.children,this.static=e.static||!1,this.size=e.items,this.gutter=e.gutter,this.maxColumns=e.maxColumns||!1,this.useMin=e.useMin||!1,this.useTransform=e.useTransform,this.animate=e.animate||!1,this.started=!1,this.init()};return n.prototype.init=function(){if(this.ready()&&!this.started){this.container.style.position="relative";for(var t=0;t<this.items.length;t++){var e=this.items[t].style;e.position="absolute",this.animate&&(e.transition=(this.useTransform?"transform":"top, left")+" 0.2s ease")}this.started=!0}},n.prototype.colWidth=function(){return this.items[0].getBoundingClientRect().width+this.gutter},n.prototype.setup=function(){var t=this.container.getBoundingClientRect().width,e=this.colWidth(),i=Math.floor(t/e)||1,n=[];this.maxColumns&&i>this.maxColumns&&(i=this.maxColumns);for(var s=0;s<i;s++)n[s]={height:0,index:s};return{cols:n,wSpace:t-i*e+this.gutter}},n.prototype.nextCol=function(t,e){return this.useMin?i(t):t[e%t.length]},n.prototype.positionItems=function(){var t=this.setup(),e=t.cols,i=t.wSpace,n=0,s=this.colWidth();i=Math.floor(i/2);for(var o=0;o<this.items.length;o++){var r=this.nextCol(e,o),a=this.items[o],h=r.height?this.gutter:0,c=r.index*s+i+"px",u=r.height+h+"px";this.useTransform?a.style.transform="translate("+c+", "+u+")":(a.style.top=u,a.style.left=c),r.height+=a.getBoundingClientRect().height+h,r.height>n&&(n=r.height)}this.container.style.height=n+"px"},n.prototype.ready=function(){return!!this.static||this.items.length>=this.size},n.prototype.getReady=function(){var t=this,e=setInterval(function(){t.container=document.querySelector(t.containerClass),t.items=t.container.children,t.ready()&&(clearInterval(e),t.init(),t.listen())},100)},n.prototype.listen=function(){var t=this;if(this.ready()){var e;window.addEventListener("resize",function(){e||(e=setTimeout(function(){t.positionItems(),e=null},200))}),this.positionItems()}else this.getReady()},n});