refactor templates layout

@see https://gohugo.io/templates/new-templatesystem-overview/

layouts/_shortcodes/figure.html

@@ -0,0 +1,67 @@
+<!--
+    Shortcode to render a media file as part of content where the place in text flow is not important.
+
+    @params src Resource `src` path.
+    @params link  URI or Page Resource to wrap resource in. Optional.
+    @params rel Force relationship value. Optional.
+-->
+
+<!-- Variable assignment -->
+
+{{- $src := $.Page.Resources.GetMatch ( .Get "src" ) -}}
+{{- $linkedResource := $.Page.Resources.GetMatch ( .Get "link" ) -}}
+{{- $valid_rel_values := partialCached "util/get_valid_rel_values.html" . -}}
+
+<!-- Validation -->
+
+{{- if not ( in ( slice "audio" "image" "video" ) $src.ResourceType ) -}}
+    {{- errorf "Resource '%q' resource type '%q' is not valid (%q)" ( .Get "src" ) $src.ResourceType .Page.File.Path -}}
+{{- end -}}
+
+{{- if ( not $src ) -}}
+  {{- errorf "No Page Resource found for src '%q' (%q)" ( .Get "src" ) .Page.File.Path -}}
+{{- end -}}
+
+{{- with .Get "rel" -}}
+    {{- if not ( in $valid_rel_values . ) -}}
+        {{- errorf "Invalid rel value '%q' (%q)" . .Page.File.Path -}}
+    {{- end -}}
+{{- end -}}
+
+<!-- Rendering -->
+
+<figure class="article__figure figure{{ with .Get "class" }} {{ . }}{{ end }}" role="group">
+    {{- if .Get "link" -}}
+        {{- if $linkedResource }}
+          <a href="{{ $linkedResource.RelPermalink }}"{{ with .Get "rel" }} rel="{{ . }}"{{ end }}>
+        {{ else }}
+          <a href="{{ .Get "link" }}">
+        {{ end }}
+    {{- end -}}
+
+    {{- if eq $src.ResourceType "image" -}}
+      {{- partial "media/picture.html" ( dict "src" $src ) -}}
+
+    {{- else if eq $src.ResourceType "audio" -}}
+        {{- partial "media/audio.html" $src -}}
+
+    {{- else if eq $src.ResourceType "video" -}}
+        {{- partial "media/video.html" ( dict "src" $src "page_file_path" .Page.File.Path ) -}}
+
+    {{- else if ( or ( ne $src.ResourceType "image" ) ( ne $src.ResourceType "video" ) ) -}}
+        {{- errorf "No handling for resource of type %q" $src.ResourceType -}}
+    {{- end -}}
+    
+    {{- if .Get "link" }}</a>{{ end -}}
+
+    {{- if or ( .Get "caption" ) ( .Get "title" ) -}}
+        <figcaption class="figure__caption{{ if not ( or ( .Get "caption" ) ( .Get "title" ) ) }} figure__caption--no-height{{ end }}">
+            {{- with .Get "title" -}}<h4 class="figcaption__title">{{ . | markdownify | safeHTML }}</h4>{{- end -}}
+            {{- with .Get "caption" -}}<p class="figcaption__caption">{{ . | markdownify | safeHTML }}</p>{{- end -}}
+        </figcaption>
+    {{- end -}}
+
+    {{- if ( isset $src.Params "attr" ) -}}
+        {{- partial "media/attr.html" ( dict "pc" . "sc" $ "params" $src.Params ) -}}
+    {{- end -}}
+</figure>