Need to upgrade unified to v10

[Zamiell]

This plugin no longer works out of the box with remark, because it depends on a version of unified that is too old.

Please upgrade the unified dependency to 10.0.1 so that your users can use this plugin again without hard-coding their package.json files to out of date versions of all other remark tools in the ecosystem.

[factoidforrest]

Big +1 on this. I tried to figure out how to fix the code but the unified docs are...sparse on how to write plugins. The issue seems to come with the way the plugin extends Parser.

I'll definitely submit a PR if I get it working. Someone with more unified experience would really help out, though