Make icons for selecting files and directories distinguishable
Addresses https://bugs.kde.org/show_bug.cgi?id=398927 (for kompare only)
This is a temporary fix until a new document-open icon is made.
The document-new icon is commonly implemented as a plain document icon with a plus sign (at least in popular icons, some linked below), so it can be interpreted as "adding a file to be compared".
Edited by Jan Paul Batrina