This reverts commit 4aa0ee61.

Mostly, removal of old code that had been commented out instead of
removed

When the time comes to merge dev into master (for real), the
following may be useful:
https://metlos.wordpress.com/2012/01/13/
git-merging-after-a-revert/

added 'supportedDragActions' function to replace functionality provided by 'setSupportedDragActions' function (obsolete)

Sankore 1224 z-layer reordering amended Delegate button progressbar added retrieving data from the internet

Imported to library pictures has unique names.

Added items has icons.

Items duplication adapted to new ideology of adding media items on the board.