Liquid date filter

[kstep]

The PR contains one feature and one fix. I can split it up into two PRs if you like, but I feel like the fix is too small for a separate PR.

The feature is a new date filter so that one can do post.date | date:"%d/%m/%y" in liquid templates (example usage: https://github.com/kstep/kstep.github.com/blob/master/src/index.liquid#L17). Although it seems like liquid parser contains another bug: it doesn't parse filter arguments correctly, so I can't use spaces in the date filter arguments (I worked it around by using   entity instead).

The fix is the incorrect YAML header splitting from markdown files. It splits files by all instances of --- separator, while it should use the first one only. The fix is pretty obvious and self-explanatory.

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This change is

[johannhof]

Hi there! Thank you for helping out! The date filter is actually part of the default set of filters in Liquid, we're just missing it in liquid-rust right now. It would be great if you could open another PR against https://github.com/cobalt-org/liquid-rust/, see also cobalt-org/liquid-rust#11

Please remove the date filter from this PR as well, so that we can merge the small fix.

As for the filter parsing issue, can you please open an issue in liquid-rust with a really small example of what does not work?

Thanks 👍

[kstep]

Ok, I removed the commit with the date filter. I will prepare an example for the bug and post a bug report later today. As for the date filter, I need it now, so I will keep on using my branch of cobalt for my blog. I will repeat the filter implementation for liquid repo later this week.

[kstep]

See cobalt-org/liquid-rust#41 for the bug report.

[kstep]

See cobalt-org/liquid-rust#42 for date filter implementation in liquid source tree.

[johannhof]

👍