PageEx and SubCaption

New PageEx blocks greatly simplified the creation of multiple pages of the same type. Now we don't have to use Page callbacks in most cases. But I think there is one more command that would be very useful to put to PageEx block. It is the SubCaption command. I suppose that everybody would like to have different captions for a multiple pages of the same type.

Thanks for consideration of my request.

It's the caption command that sets the caption for PageEx blocks. Oops... Forgot to document that, will do soon.