* app_name: To be used in filters when no clients are found.
* max_width: Allow to set it from the rules, it might be different
when a `widget_template` is used.
* widget_template: Now it can be set from the rules without further
boilerplate code.
The old preset code had a primitive implementation of the rule API
used in `naughty.dbus`. Now that `gears.matcher` is extracted from
`awful.rules`, it is possible to share the code.
The first step is to only enable the old API when the new
`request::preset` isn't connected. This is the same way the legacy
popup is only enabled when nothing is connected to `request::display`.