perf: disable Academicons integration by default

Increase performance.

To enable, add the following to bottom of `params.toml`:

[icon.pack]
  ai = true  # Academicons icon pack https://jpswalsh.github.io/academicons/

exampleSite/config/_default/params.toml

@@ -290,3 +290,9 @@ plugins_js  = []
 [cms]
   # See https://sourcethemes.com/academic/docs/install/#install-with-web-browser
   netlify_cms = true
+
+############################
+## Icon Pack Extensions
+############################
+[icon.pack]
+  ai = false  # Academicons icon pack https://jpswalsh.github.io/academicons/

layouts/partials/site_head.html

@@ -61,7 +61,9 @@
     <link rel="stylesheet" href="{{ printf "/css/vendor/%s" ($scr.Get "vendor_css_filename") | relURL }}">
   {{ else }}
     {{ $scr.Set "use_cdn" 1 }}
-    {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\">" (printf $css.academicons.url $css.academicons.version) $css.academicons.sri | safeHTML }}
+    {{ if site.Params.icon.pack.ai }}
+      {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\">" (printf $css.academicons.url $css.academicons.version) $css.academicons.sri | safeHTML }}
+    {{ end }}
     {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\">" (printf $css.fontAwesome.url $css.fontAwesome.version) $css.fontAwesome.sri | safeHTML }}
     {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\">" (printf $css.fancybox.url $css.fancybox.version) $css.fancybox.sri | safeHTML }}