URLs in a['href'] should be escaped for LaTeX

[hperl]

An URL such as in a a['href'] can contain URL escape codes, which all start with a %. The LaTeX-converter should escape all % to \% using escape(), or otherwise the unescaped % will be treated like a comment in LaTeX, corrupting the file.

This pull request fixes this by calling escape() on the URL.

[gettalong]

Thanks!

[mkamensky]

I think this is actually wrong, escaping breaks for instance urls with a tilde in them. The hyperref manual says that " The special characters # and ̃ do not need to be escaped in any way.". Unfortunately, it does not say anything about other characters...

[gettalong]

@mkamensky Thanks for your comment - do you have any test cases for this?

[mkamensky]

Yes, this comes from my real life example:

echo '<https://www.math.bgu.ac.il/~amyekut/teaching/2016-17/der-cats-III/course_page.html>' | ruby -rkramdown -e 'puts Kramdown::Document.new(ARGF.read).to_latex'

It produces

\href{https://www.math.bgu.ac.il/\ensuremath{\sim}amyekut/teaching/2016-17/der-cats-III/course\_page.html}{https://www.math.bgu.ac.il/\ensuremath{\sim}amyekut/teaching/2016-17/der-cats-III/course\_page.html}

which does not compile. Thanks!

[gettalong]

@mkamensky Sorry for the long delay...

I have tested this now with #, % and ~: Seems to work fine without escaping. As you mentioned, the hyperref package doesn't say much about escaping but I found this answer on StackExchange.

Therefore I have changed the code to just escape the percent sign and nothing else. Seems to do what it should so far.

Will be in the next release!

[mkamensky]

@gettalong Thanks!