Include all photos as links in the RSS and Atom feeds, instead of just the thumbnail

- Move photo_thumbnail.html to photos/thumbnail.html
- Add a photos/list.html partial that returns a list of photos for the current
  page
- Use the template above everywhere we need a list of photos for the page

layouts/photos/atom_entry.atom

@@ -1,11 +1,10 @@
-{{- $thumbnail := partial "images/photo_thumbnail.html" . -}}
+{{- $thumbnail := partial "photos/thumbnail.html" . -}}
 <entry>
   {{ partial "atom_entry_metadata.xml" . }}
   <link rel="enclosure" href="{{ $thumbnail.Permalink }}" type="{{ $thumbnail.MediaType }}" length="{{ len $thumbnail.Content }}" />
-  {{- $inlineThumbnail := partial "images/photo_thumbnail.html" (dict "Page" . "Width" 1280 "Height" 1280) -}}
   <content type="html">{{ `<![CDATA[` | safeHTML }}
-    {{- with $inlineThumbnail -}}
-    <img src="{{ .Permalink }}">
+    {{- range partial "photos/list.html" . -}}
+    <img src="{{ .Permalink }}"{{ with .Params.alt }} alt="{{ . }}"{{ end }}>
     {{- end -}}
     {{- .Content -}}
   ]]></content>