Revert "Use only `div` or `li` elements as placeholder."

This reverts commit b2e32484c05131046d9ef75d56297e8794298cbb.

Conflicts:
	jquery.sortable.js
Revert "Use detach instead of hide on the dragged element"

This reverts commit e93fcb6771f4cb646031373f07b81512d10e5d6a. Detaching
breaks forcePlaceholderSize.