[Dillo-dev] patch: image inputs

It works on the sites I tried, and the data sent looks right for other cases, but: - To get click position, I used event_x() and event_y() in fltkui.cc because they happened to have the right values in them and I didn't know the proper place to look for this information. - If the image could not be loaded and you click on the alt text, the click position is sent, even though it's not meaningful. - I don't prevent the image from being loaded even when automatic image loading is disabled (but I'm the only person who would notice anyway). (I would have to be able to get button 3 to bring up the image menu.)