Attach/New Post/Edit Post: show files and images separately in the Edit form

[urbansheep]

At the moment attached files and images are displayed in the order of attaching and inline. Sort of.

It seems that pictures should be added to a separate container, stacked horizontally from left to right, while music (or other) files should be stacked below as a list, vertically from top to bottom.

[epicmonkey]

kind of dup of #616

[urbansheep]

Not a dup, imho, #616 relates to file previews, this one is about mixed media posts which look really weird now when composing.