Improve connectors settings display

- Move settings templates to subfolder
- Add accordion display to "General Theme Settings" in frio
- Replace hand-written template with form field includes
- Simplify sprintf(t()) structures

view/templates/settings/addons.tpl

@@ -0,0 +1,11 @@
+
+<h1>{{$title}}</h1>
+
+
+<form action="settings/addon" method="post" autocomplete="off">
+<input type='hidden' name='form_security_token' value='{{$form_security_token}}'>
+
+{{$settings_addons}}
+
+</form>
+