Extend drupal_add_js to allow for external scripts

I have run into the situation were I need to include an external javascript file. The current drupal_add_js function does not support this.

I was able to very easily modify includes/common.inc to allow for this functionality. The only other issue I have is that the javascript includes are not output in the same order they were added. That could be fixed by inserting them with an arbitrary number key before of $type as the key.

$javascript[$scope][$type][$data] = array('cache' => $cache, 'defer' => $defer, 'preprocess' => (!$cache ? FALSE : $preprocess));

If that were changed to something like:

$javascript[$scope][][$type][$data] = array('cache' => $cache, 'defer' => $defer, 'preprocess' => (!$cache ? FALSE : $preprocess));

Then the items could be output in the same order they were input. The reason this would be nice is if you include a javascript file and then output some code it won't necessarily output the include first.

To allow for external javascript includes the following would need to be modified:

$no_preprocess[$type] .= '<script type="text/javascript"'. ($info['defer'] ? ' defer="defer"' : '') .' src="'. base_path() . $path . ($info['cache'] ? $query_string : '?'. time()) ."\"></script>\n";

The modification could look something like the following:

$no_preprocess[$type] .= '<script type="text/javascript"'. ($info['defer'] ? ' defer="defer"' : '') .' src="'. ($type == 'external' ? '' : base_path()) . $path . ($info['cache'] ? $query_string : '?'. time()) ."\"></script>\n";

I suppose it would also need to be done to preprocessed file:

$preprocessed .= '<script type="text/javascript" src="'. ($type == 'external' ? '' : base_path()) . $preprocess_file .'"></script>'."\n";

So basically just changing base_path() to ($type == 'external' ? '' : base_path()).

Not sure what the opinions are on this, so let me know. Would probably also be useful for 5.x, etc.