Expanding the Filter Hooks Ability

Improve the filter hooks architecture to simplify the automation logic.
Some old filter still remain unchanged. Some omitted, because the filter
is currently in no use. So this changes will not broke anything.

The following is an example results of the automated filters, inspected
using the `Filter::exist()` method on the article page:

~~~
title
article:title
description
article:description
author
article:author
fields
article:fields
shortcode
article:shortcode
content
article:content
custom:shortcode
css
custom:css
javascript
custom:javascript
article:fields.allow_comments
article:fields.lala_oo
widget
widget:search
widget:manager.menu
widget:manager
widget:tag.list
widget:tag
widget:archive.hierarchy
widget:archive
~~~

+ Add some new methods in `Weapon` and `Converter` class.