Improve breadcrumb helper

- Add support for collections
- Add support for crumb links that point to auto-generated archive pages (courtesy of Jekyll Archives plugin) and single page Liquid spaghetti pages
- Improve styling

_includes/breadcrumbs.html

@@ -1,3 +1,17 @@
+{% case site.categories.type %}
+  {% when "liquid" %}
+    {% assign path_type = "#" %}
+  {% when "jekyll-archives" %}
+    {% assign path_type = nil %}
+{% endcase %}
+
+{% if page.collection != 'posts' %}
+  {% assign path_type = nil %}
+  {% assign crumb_path = '/' %}
+{% else %}
+  {% assign crumb_path = site.categories.path %}
+{% endif %}
+
 <nav class="breadcrumbs">
   <ol itemscope itemtype="http://schema.org/BreadcrumbList">
     {% assign crumbs = page.url | split: '/' %}
@@ -15,7 +29,7 @@
       {% else %}
         {% assign i = i | plus: 1 %}
         <li itemprop="itemListElement" itemscope itemtype="http://schema.org/ListItem">
-          <a href="{{ base_path }}{% assign crumb_limit = forloop.index | plus: 1 %}{% for crumb in crumbs limit: crumb_limit %}{{ crumb | append: '/' }}{% endfor %}" itemprop="item"><span itemprop="name">{{ crumb | replace: '-', ' ' | replace: '%20', ' ' | capitalize }}</span></a>
+          <a href="{{ base_path }}{{ crumb | prepend: path_type | prepend: crumb_path }}" itemprop="item"><span itemprop="name">{{ crumb | replace: '-', ' ' | replace: '%20', ' ' | capitalize }}</span></a>
           <meta itemprop="position" content="{{ i }}" />
         </li>
         <span class="sep">{{ site.breadcrumb_separator }}</span>