Nautilus preferences: sort-directories-first should be enabled by default

The main reason being it's what previous Ubuntu/nautilus users are expecting/used to & is a bit 'cleaner'
Additional reasons to consider are it's no a menu or gui pref's option so only can be changed in dconf (editor or gsettings) which won't be apparent to most users.
Those wishing to have set to false will likely know how to do so

While only a 1 word source edit could just as well be done in the nautilus.gschema.override, i'd suspect adding this would suffice.

[org.gnome.nautilus.preferences]
sort-directories-first=true

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: nautilus 1:3.5.4-0ubuntu2 [modified: usr/share/glib-2.0/schemas/10_nautilus.gschema.override]
ProcVersionSignature: Ubuntu 3.5.0-7.7-generic 3.5.0
Uname: Linux 3.5.0-7-generic x86_64
ApportVersion: 2.4-0ubuntu6
Architecture: amd64
Date: Fri Aug 3 16:59:06 2012
GsettingsChanges:
 b'org.gnome.nautilus.window-state' b'geometry' b"'1115x655+59+24'"
 b'org.gnome.nautilus.window-state' b'sidebar-width' b'159'
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120707)
ProcEnviron:
 TERM=xterm
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: nautilus
UpgradeStatus: No upgrade log present (probably fresh install)