feat(import): add @import filter support (options.import)

Author: michael-ciniawsky

README.md

@@ -146,6 +146,32 @@ To disable `@import` resolving by `css-loader` set the option to `false`
 }
 ```
 
+#### `{RegExp}`
+
+**webpack.config.js**
+```js
+{
+  loader: 'css-loader',
+  options: {
+    import: /filter/
+  }
+}
+```
+
+#### `{Function}`
+
+**webpack.config.js**
+```js
+{
+  loader: 'css-loader',
+  options: {
+    import (url) {
+      return /filter/.test(url)
+    }
+  }
+}
+```
+
 ### `minimize`
 
 #### `{Boolean}`

src/index.js

@@ -53,7 +53,7 @@ export default function loader(css, map, meta) {
 
   // Import Plugin
   if (options.import) {
-    plugins.push(imports());
+    plugins.push(imports(options));
   }
 
   // Minifier

src/lib/Error.js

@@ -10,7 +10,12 @@
       ]
     },
     "import": {
-      "type": "boolean"
+      "anyOf": [
+        { "type": "string" },
+        { "type": "boolean" },
+        { "instanceof": "RegExp" },
+        { "instanceof": "Function" }
+      ]
     },
     "minimize": {
       "type": "boolean"