Port classnames to Hugo, Simplify class name builder

feature
1

TL;DR, see classnames - npm

class="main {{- $active }} is-active{{ end }}"

vs

{{-
$classes := classNames
  "main"
  (dict "is-active" $active)
-}}
class="{{ $classes }}"
2

In what meaning/usage?

3

It seems more complex to me.

class="main{{ cond $active `is-active` `` }}"

This may be achieved by delimit.

{{ $classes := slice 
  "main"
  (cond $active "is-active" "")
}}
class="{{ delimit $classes ` ` }}"

The empty class names will be formatted via --minify flag.