Port leading module to plugin

src/plugins/leading.js

@@ -0,0 +1,13 @@
+import _ from 'lodash'
+
+export default function () {
+  return function ({ addUtilities, config, e }) {
+    const utilities = _.fromPairs(_.map(config('leading'), (value, modifier) => {
+      return [`.${e(`leading-${modifier}`)}`, {
+        'line-height': value,
+      }]
+    }))
+
+    addUtilities(utilities, config('modules.leading'))
+  }
+}