De-duplicate list attribute values

[stevenvachon]

such as class, ping and rel.

<a class="class1   class2 class2" ping="http://domain1.com, http://domain2.com" rel="me me   external">

would compile to:

<a class="class1 class2" ping="http://domain1.com,http://domain2.com" rel="me external">

These would be handy: list-to-array, dupe

If we wanted to de-dupe URL lists (such as ping), we could use url-relation.

[maltsev]

For now I only implemented class, rel, and ping minification as deduplicateAttributeValues module. I'm going to release it in version 0.2.0.

[maltsev]

Released: 0.2.0.