fix: add support for external_link in archives

Improves consistency: external projects are now opened in new tab whether they are viewed from the Portfolio widget or archive page.

Fix #1525

layouts/_default/list.html

@@ -9,18 +9,24 @@
 
   {{ $paginator := .Paginate .Data.Pages }}
   {{ range $paginator.Pages }}
-  <div>
-    <h2><a href="{{ .RelPermalink }}">{{ .Title }}</a></h2>
-    <div class="article-style">
-      {{ if .Params.summary }}
-      {{ .Params.summary | plainify | emojify }}
-      {{ else if .Params.abstract }}
-      {{ .Params.abstract | plainify | emojify | truncate 250 }}
-      {{ else if .Summary }}
-      {{ .Summary | plainify | emojify }}
-      {{ end }}
+    {{ $link := .RelPermalink }}
+    {{ $target := "" }}
+    {{ with .Params.external_link }}
+      {{ $link = . }}
+      {{ $target = "target=\"_blank\" rel=\"noopener\"" }}
+    {{ end }}
+    <div>
+      <h2><a href="{{$link}}" {{ $target | safeHTMLAttr }}>{{ .Title }}</a></h2>
+      <div class="article-style">
+        {{ if .Params.summary }}
+          {{ .Params.summary | plainify | emojify }}
+        {{ else if .Params.abstract }}
+          {{ .Params.abstract | plainify | emojify | truncate 250 }}
+        {{ else if .Summary }}
+          {{ .Summary | plainify | emojify }}
+        {{ end }}
+      </div>
     </div>
-  </div>
   {{ end }}
 
   {{ partial "pagination" . }}