[BZ#683616] Indicate symlink and show target in folder comparison

Submitted by El Piraña

Description

Detect when a file or folder is in fact a (symbolic) link and represent it in someway, for example with a little arrow over the icon like Nautilus does, and maybe a little number with the number of copies on hard links. This would allow to identify when a file or folder is on other place, for example when comparing source code modules from Node.js or Python and local modifyied copies, so modifying them would make problems.

Later, as a more advanced improvements, it would refresh the (full?) diff tree when a (hard?) link copy is modified, since in fact the file have been "modified" in several places, and also it would be useful to add an option to follow the links as currently does, or don't follow them making in fact a link and a real file different items.