Allow tooltips for section headers with 'question' icon

[ddb4github]

Is your feature request related to a problem? Please describe.
Show form tooltip for section header(type=spacer) with 'question' icon

Describe the solution you'd like

1. support 'description' for 'spacer' item
2. call display_tooltip function

Additional context

--- html_form.php	2019-07-02 21:43:04.000000690 +0800
+++ html_form.php	2019-07-24 13:27:27.000000453 +0800
@@ -61,7 +61,9 @@
 			} elseif ($field_array['method'] == 'spacer') {
 				$collapsible = (isset($field_array['collapsible']) && $field_array['collapsible'] == 'true');
 
-				print "<div class='spacer formHeader" . ($collapsible ? ' collapsible':'') . "' id='row_$field_name'><div class='formHeaderText'>" . html_escape($field_array['friendly_name']) . ($collapsible ? "<div class='formHeaderAnchor'><i class='fa fa-angle-double-up'></i></div>":'') . '</div></div>';
+				print "<div class='spacer formHeader" . ($collapsible ? ' collapsible':'') . "' id='row_$field_name'><div class='formHeaderText'>" . html_escape($field_array['friendly_name']);
+				print '<div class="formTooltip">' . display_tooltip($field_array['description']) . '</div>';
+				print ($collapsible ? "<div class='formHeaderAnchor'><i class='fa fa-angle-double-up'></i></div>":'') . '</div></div>';
 			} else {
 				// Make a row using a div
 				if (isset($config_array['force_row_color'])) {