Give each row in a table a heading

The first columns of our tables are always headings for the
subsequent columns, even though they go horizontally.

HTML has the `<th>` tag, which doesn’t just have to be used for headings
along the top of a table. So this commit changes the first column to be
a `<th>`.

This then allows us to style these elements differently, specifically
making them 50% wide. This makes pages like the dashboard align more
nicely.

app/templates/components/table.html

@@ -55,12 +55,24 @@
   </td>
 {%- endmacro %}
 
+{% macro row_heading() -%}
+  <th class="table-field">
+    <span>{{ caller() }}</span>
+  </th>
+{%- endmacro %}
+
 {% macro index_field(text) -%}
   <td class="table-field-index">
     <span>{{ text }}</span>
   </td>
 {%- endmacro %}
 
+{% macro date_field(text) -%}
+  <td class="table-field-date">
+    <span>{{ text }}</span>
+  </td>
+{% endmacro %}
+
 {% macro text_field(text) -%}
   {% call field() %}
     {{ text }}