Consider renaming Twig filters into something more appropriate

[Chi-teck]

I think "filter" term is misused. A filter is something that filters out incoming input but Twig filters are more than that. They may change the incoming data and even create new data. I suppose they are more like converters or transformers.

[fabpot]

A filter should not change the input and should never create new data.
In any case, we won't change the name now as it would be a major BC break.
The term filter is also used in many other Twig-like templating system in other languages,

[Chi-teck]

A filter should not change the input

Well, most of core Twig filters do change the input. Technically filters like html_to_markdown are converters not filters. And filters like default do create new data.
Anyway I agree changing the name without BC break would be really hard.