Add Image Channel Element

[amiad]

I tried to use this library but I need image channel.
Please add its.

[kAlvaro]

As workaround, you can extend \Suin\RSSWriter\Channel and add your own logic. The tricky bit is that <image> needs to be inserted before <item> and the library does not provide specific hooks to do that.

I wrote a little custom Channel for my personal use. It doesn't implement all fields but it should be easy to improve.