feat: add pdf.less for better export with dw2pdf

[micgro42]

dw2pdf uses the print.css if there is no pdf.css available. It also allows the usage of the style.css for configured plugins. However, wrap's print.css removes the left margin from note boxes and causes the text to be displayed above the icon in the resulting pdf.

Adding a pdf.less fixes that problem and allows for feature changes affecting pdf only.

To work its magic, this pull request depends on the bugfix in splitbrain/dokuwiki-plugin-dw2pdf#325 .

[selfthinker]

I finally had a look at this and am nearly happy to merge. I would make two changes:

• I think it makes more sense to keep the spoiler styles out of this so they look like they look on the screen.
• The styles overwriting the screen styles for .wrap_onlyprint are missing. This works:

.dokuwiki div.wrap_onlyprint {
    display: block;
}
.dokuwiki span.wrap_onlyprint {
    display: inline;
}

I would also add some comments so it matches the commenting style of the other CSS files and adds information on how and when the file is used and that it's usually used together with style.css. But I can do that in a separate commit.

Slightly related, what do you think of #130?

[micgro42]

Implemented your comments.

Since we now should have working onlyprint and noprint, I don't really see the use-case for having an additional onlypdf class as requested in #130. I would advice against it. Further, they could still manually implement it with userstyles, if they really need it in addtion to the existing classes.

[selfthinker]

Thanks. I've squashed your commits and made some more changes to avoid duplication. After using Less everywhere (#166), I created a shared LESS file in 9c20817.