added opportunity to easier extend the pipeline

Author: mightyaleksey

src/index.js

@@ -63,22 +63,25 @@ export default function setup(opts = {}) {
     return void (plugins = customPlugins);
   }
 
-  plugins = [];
-
+  const prepend = get('prepend', null, 'array', opts) || [];
+  const append = get('append', null, 'array', opts) || [];
   const mode = get('mode', null, 'string', opts);
-  plugins.push(mode
-    ? new LocalByDefault({mode: opts.mode})
-    : LocalByDefault);
-
   const createImportedName = get('createImportedName', null, 'function', opts);
-  plugins.push(createImportedName
-    ? new ExtractImports({createImportedName: opts.createImportedName})
-    : ExtractImports);
-
   const generateScopedName = get('generateScopedName', null, 'function', opts);
-  plugins.push(generateScopedName
-    ? new Scope({generateScopedName: opts.generateScopedName})
-    : Scope);
+
+  plugins = [
+    ...prepend,
+    mode
+      ? new LocalByDefault({mode: opts.mode})
+      : LocalByDefault,
+    createImportedName
+      ? new ExtractImports({createImportedName: opts.createImportedName})
+      : ExtractImports,
+    generateScopedName
+      ? new Scope({generateScopedName: opts.generateScopedName})
+      : Scope,
+    ...append,
+  ];
 }
 
 /**