Use goblog's shared _powered_by partial for the footer credit

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.4.0
+
+- The footer's "Powered by goblog" line comes from goblog's shared `_powered_by` partial instead of being written out in the theme. It now links to [goblog.live](https://www.goblog.live) rather than the GitHub repository, and a site can hide it with the **Show "Powered by goblog"** setting under Admin → Settings → Appearance (goblog #644).
+- **Requires goblog 0.13.0**, the first release with the partial; on anything older the theme's `footer.html` references a template that does not exist.
+
 ## 1.3.0
 
 - Signing in with GitHub is goblog's job now. The button is a plain link to `/login/github`; the theme no longer assembles the authorize URL in an inline script, where `window.location` went into `redirect_uri` unescaped, nor handles the `?code=` that came back. goblog completes the exchange server-side against a `state` it minted, so a code obtained for one account can no longer be replayed into another visitor's browser (goblog #631, #637).

goblog-theme.json

@@ -4,6 +4,6 @@
   "description": "Misty greens, a soft serif and a full-bleed forest backdrop — goblog's forest theme.",
   "author": "Jason Ernst",
   "license": "Apache-2.0",
-  "min_goblog_version": "0.12.0",
+  "min_goblog_version": "0.13.0",
   "homepage": "https://github.com/goblogplatform/goblog-theme-forest"
 }

static/css/goblog.css

@@ -104,3 +104,7 @@ video {
   text-overflow: ellipsis;
   white-space: nowrap;
 }
+
+/* The "Powered by goblog" credit is goblog's shared _powered_by partial; its
+   link takes the colour of the footer line around it. */
+.powered-by a { color: inherit; }

templates/footer.html

@@ -6,7 +6,7 @@
           <p style="font-weight: 600; font-size: 14px; margin-bottom: 8px; color: #d4e4d4;">{{ .settings.site_title.Value }}</p>
           {{ with .plugin_footer_html }}{{ . | rawHTML }}{{ end }}
         </div>
-        <p style="color: rgba(255,255,255,0.4); font-size: 11px; margin: 0;">Powered by <a href="https://github.com/goblogplatform/goblog" style="color: rgba(255,255,255,0.4);">goblog {{ .version }}</a></p>
+        <p style="color: rgba(255,255,255,0.4); font-size: 11px; margin: 0;">{{ template "_powered_by" . }}</p>
       </div>
     </div>
   </div>