Subform conflict with dragndrop_upload due to rewriting #name

Subform doesn't work with modules like dragndrop_upload because it rewrites #name of subform elements, and makes it too late.

The issue is with order of pre_render hooks attached to subform. In my case, subform's pre_render is called at the end, after other pre_render functions got executed. In effec, dragndrop_upload uses invalid, "old" #name.