added support for ignore_front_matter

[GarthDB]

I use mdl with Jekyll posts, but most have issues with content in the YAML front matter. This pull request would make it possible to ignore the front matter, but markdownlint would report errors with the correct line numbers even thought it would consider the first line to be line following the front matter.

I do think my code could use some clean up and am looking for some mentoring on this issue.

This pull request would close #130

[DavidAnson]

This is something I have done in the Node version in response to an issue/PR. There are additional tests there that may be useful.

DavidAnson/markdownlint@a467f8b

[GarthDB]

@DavidAnson Yeah, I appreciate it being in the node version, because of that I have been using node in my jekyll projects to lint, which I shouldn't have to do, but the front matter gets in the way.

[mivok]

Hi Garth,

Thanks for your contribution. You mentioned the code needing cleanup, so I looked through and made a few changes and have put comments here. Overall it looks fine, and the changes were pretty minor:

• I moved the offset method in lib/mdl/doc.md to be an attr_reader line for consistency with other attributes. Attr_reader is a shorthand way of saying the same thing as you wrote.
• I changed the [\s\S] to just be a dot in the regex and enabled multiline mode on the regex with /m at the end. I think this better communicates the intent (to match any character).
• line_offset is set early on in the main mdl.rb file, and then only used once after that. I got rid of the additional variable assignment and just used doc.offset directly.
• When loading the config option, it will already be a boolean, and so you don't need to include the ternary operator ? true : false afterwards and can just use Config[:ignore_front_matter] directly.

[GarthDB]

Excellent, thanks @mivok !

[GarthDB]

@mivok what's your estimated release looking like - I'd love to move these changes into our code climate workflow.

[mivok]

I'm aiming for either later today or tomorrow for the next release.

[GarthDB]

Oh, awesome. I'll keep my eye open and make the appropriate pull requests after!

Thanks again for all the work.