add a css class with the column name to table headers, and document the behavior

fixes #264

Author: lovasoa

examples/official-site/sqlpage/migrations/01_documentation.sql

@@ -544,7 +544,12 @@ The `color` property sets the color of each series separately, in order.
       ]'));
 
 INSERT INTO component(name, icon, description) VALUES
-    ('table', 'table', 'A table with optional filtering and sorting. Unlike most others, this component does not have a fixed set of item properties, any property that is used will be rendered directly as a column in the table.');
+    ('table', 'table', 'A table with optional filtering and sorting.
+Unlike most others, this component does not have a fixed set of item properties, any property that is used will be rendered directly as a column in the table.
+Tables can contain rich text, including images, links, and icons. Table rows can be styled with a background color, and the table can be made striped, hoverable, and bordered.
+
+Advanced users can apply custom styles to table columns using a CSS class with the same name as the column, and to table rows using the `_sqlpage_css_class` property.
+');
 
 INSERT INTO parameter(component, name, description, type, top_level, optional) SELECT 'table', * FROM (VALUES
     -- top level

sqlpage/templates/table.handlebars

@@ -18,6 +18,7 @@
                             {{#each this}}
                                 {{#if (not (starts_with @key '_sqlpage_'))}}
                                 <th class="
+                                    {{~@key~}}
                                     {{~#if (array_contains ../../align_right @key)}} text-end {{/if~}}
                                 ">
                                     {{~#if ../../sort~}}