[manage view] cleanup manage view and user menu
* drop code that shouldn't be there (e.g. folders handling)
* add a section displaying site management actions, some of them
were initially in the user's drop down menu, which now only have
a 'manage' link with regards to management actions
* stop displaying 'system' and 'schema' entities by default, only
'application' entities
* put 'gc', 'registry' and 'info' views as tabs of a generic
'server information' view
<table class="attributeForm" style="width:100%;"
tal:attributes="id tab_id | nothing;
class tab_class | nothing;">
<tr tal:iter="widget lines">
<th class="labelCol" tal:content="structure python:widget.render_label(entity)">attrname</th>
<td tal:define="error python:widget.render_error(entity)" style="width:100%;"
tal:attributes="class python:error and 'error' or nothing">
<div tal:replace="structure error">error message if any</div>
<div tal:replace="structure python:widget.edit_render(entity)" >widget (input, textarea, etc.)</div>
<div tal:replace="structure python:widget.render_help(entity)">format help if any</div>
</td>
</tr>
</table>