Fix Thumbnail preview

[relikd]

Took some time to figure that out but quite an easy fix for issue #88.

[frankrolf]

I would be thankful and grateful if this PR could be merged.
(If this is not possible, I’d appreciate instructions for building the plugin myself.)

Thanks!

[relikd]

I was writing this tutorial when I realized that the rendering didn't actually took place as intended. It was removed with merge #91 and replaced with a plain text output. (don't ask why I was developing this fix on an old branch, I don't know)
Now the thumbnail preview should work properly!

Anyway, here is the paste-it-in-Terminal-and-everything-is-done-automatically script:

cd ~/Downloads
git clone https://github.com/relikd/qlmarkdown qlmarkdown-relikd
cd qlmarkdown-relikd
rm -rf discount/
git clone git://github.com/Orc/discount.git discount
cd discount
git checkout v2.2.6
cd ..
xcodebuild -configuration Release
cp -rf build/Release/QLMarkdown.qlgenerator ~/Library/QuickLook

But maybe @toland can now merge it? :)

[relikd]

I also noticed that tables are not rendered?

[frankrolf]

Tables are (afaik) not part of the official .md spec – they are an addition which only works on GitHub.