Application Icons

This adds one svg file with all Qt related application icons.

Change-Id: Ie9893e2baaef822c55348946f84600ea141d121f
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>

src/tools/icons/GenericDocumentIcon.iconset/readme.txt

+This directory needs to contain the files
+
+  icon_128x128.png
+  icon_128x128@2x.png
+  icon_16x16.png
+  icon_16x16@2x.png
+  icon_256x256.png
+  icon_256x256@2x.png
+  icon_32x32.png
+  icon_32x32@2x.png
+  icon_512x512.png
+  icon_512x512@2x.png
+
+On OSX, they are obtainable by executing the following command:
+iconutil -c iconset /System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/GenericDocumentIcon.icns