flexible indentation width

[aogier]

Hi, it would be neat if every line indentation could be indented by $indent_width or another $indent_width more, or less. I'll make an example: when i write Dockerfiles, I usually double indent this kind of pieces:

RUN apk add --no-cache \
        gcc \
        python-dev \
    && pip install \
        ansible

this make the whole stuff a lot more readable, and in fact I'm not alone using that style. I can't find a way to properly configure this behaviour on current vscode editorconfig plugin, I don't think we have such a specification anyway.

The implementation idea is to indent every line with a specified indent_width but tolerate previous_width + indent_width or previous_width - indent_width.

What do you think? Thank you, ciao!