DiffEditor: Avoid "jump to file" for directories and nonexistent files

Submodule diff sample (sub is the submodule's root directory):

diff --git a/sub b/sub
index 6ae5025..4b26500 160000
--- a/sub
+++ b/sub
@@ -1 +1 @@
-Subproject commit 6ae5025c9a66767e90cd320f9661e7694f7ea8b5
+Subproject commit 4b2650066d4143e8b7a9f4b19e46b96996a1dd90

Change-Id: I388de5bc50ceb1fcfc31a3a70ce8328c83fafa71
Reviewed-by: Jarek Kobus <jaroslaw.kobus@digia.com>
Doc: Rename some images from "targets" to "kits"

Change-Id: Ibb5475e15c7f2fa845e8060cf176296693769766
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
QmlDesigner: Change name to itemVisible

Change-Id: I9eb034292f79da8d3060f7f4a917a9e2c11eeb83
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>