Preserve Liquid tags contents

[duailibe]

Closes #3695

[ikatyang]

It seems the -? part is unnecessary, {%- something -%} is already included in {% something %}, or are those leading/trailing spaces necessary?

And I think string.match(regex) should be better than regex.exec(string) since we do not use multiple exec calls, what do you think?

[duailibe]

I think you're right about -?. I don't understand what you mean about the leading/trailing spaces.

I don't know if one is better. I was using exec specifically because I only care about the first match but that was before I was using ^. But sure, I'll change it

[ikatyang]

I don't understand what you mean about the leading/trailing spaces.

I meant this:

{% something %}
  ^         ^

[duailibe]

They're not mandatory from what I could gather from parsers implementations

[j-f1]

Let’s add some examples from the issue:

{% include_relative _installations/tarball.md %}
{% cloudinary nice_prefix_-_for_the_filename.jpg %}

[j-f1]

Just what @ikatyang said.