Add URI support to add_editor_style()

[dwieeb]

Currently add_editor_style() only allows for CSS files to be added that are relative in location to the current theme's stylesheet_directory or template_directory, meaning it can only be used by theme authors. Let's keep that functionality, but add the ability to attach a CSS file via URI. This way, plugin authors can use it to add editor styles.

An example of why this might be necessary is a microformat plugin where the user can style microformats differently by adding certain CSS files by the user's choice. Right now, we can only see a change like that when we click preview.

So it would be nice if plugins could use this function as well as themes.

I've attached a potential patch.

Potential patch. Mildly tested.

please use .diff or .patch for the patch so it's easier to read

Reuploaded as a diff file

Right-o