Implement inheritance tree for host classes

Documentation pages for host classes now show the full inheritance tree instead
of just the immediate parent.

lib/puppetx/yardoc/yard/code_objects/host_class_object.rb

@@ -33,5 +33,20 @@ module Puppetx::Yardoc::YARD::CodeObjects
       yield(obj) if block_given?
       obj
     end
+
+    def inheritance_tree
+      if parent_class.is_a?(HostClassObject)
+        # Cool. We got a host class. Return self + parent inheritance tree.
+        [self] + parent_class.inheritance_tree
+      elsif parent_class.is_a?(YARD::CodeObjects::Proxy)
+        # We have a reference to a parent that has not been created yet. Just
+        # return it.
+        [self, parent_class]
+      else
+        # Most likely no parent class. But also possibly an object that we
+        # shouldn't inherit from. Just return self.
+        [self]
+      end
+    end
   end
 end

lib/puppetx/yardoc/yard/templates/default/hostclass/html/box_info.erb

@@ -3,8 +3,13 @@
   <% if object.parent_class %>
     <dt class="r<%=n%>">Inherits:</dt>
     <dd class="r<%=n%>">
-      <span class="inheritName"><%= linkify object.parent_class %></span>
-      <%# TODO: Add inheritance tree. %>
+      <span class="inheritName"><%= linkify object.parent_class, object.parent_class.path %></span>
+      <ul class="fullTree">
+        <% object.inheritance_tree.reverse.each_with_index do |obj, i| %>
+          <li class="next"><%= obj == object ? obj.path : linkify(obj, obj.path) %></li>
+        <% end %>
+      </ul>
+      <a href="#" class="inheritanceTree">show all</a>
     </dd>
     <% n = 2 %>
   <% end %>