Load from file URL

[Franklin Yu]

In CommonJS we have __dirname. In ES modules we use import.meta.url instead, which is a file: URL. It would be great if serveFolder also works with file URL.

The related source should be

carlo/lib/carlo.js

Lines 159 to 161 in 2c76e87

 serveFolder(folder = '', prefix = '') { 
   this.www_.push({folder, prefix: wrapPrefix(prefix)}); 
 } 

I can PR if that is preferred.