Add custom favicon if needed (alshedivat#386)

_config.yml

@@ -15,7 +15,8 @@ footer_text: >
   Photos from <a href="https://unsplash.com" target="_blank">Unsplash</a>.
 keywords: jekyll, jekyll-theme, academic-website, portfolio-website  # add your own keywords or leave empty
 
-icon: 🌎 # the emoji used as the favicon
+icon: 🌎 # the emoji used as the favicon (alternatively, provide image name in /assets/img/)
+
 url:  # the base hostname & protocol for your site
 baseurl:  # the subpath of your site, e.g. /blog/
 last_updated: false # set to true if you want to display last updated in the footer

_includes/head.html

@@ -1,4 +1,3 @@
-
     <!-- Metadata, OpenGraph and Schema.org -->
     {% include metadata.html %}
 
@@ -15,9 +14,11 @@
     <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/jwarby/jekyll-pygments-themes@master/{{ site.highlight_theme_light | append: '.css' }}" media="none" id="highlight_theme_light" />
 
     <!-- Styles -->
-    {% if site.icon != empty -%}
-    <link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>{{ site.icon }}</text></svg>">
-    {%- endif %}
+    {% if site.icon.size == 1 %}
+    <link rel="shortcut icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>{{ site.icon }}</text></svg>">
+    {% elsif site.icon != blank %}
+    <link rel="shortcut icon" href="{{ site.icon | prepent: '/assets/img/' | relative_url}}"/>
+    {% endif %}
     <link rel="stylesheet" href="{{ '/assets/css/main.css' | relative_url }}">
     <link rel="canonical" href="{{ page.url | replace:'index.html','' | absolute_url }}">