[Bf-codereview] Paths and Windows Installer Fixes (issue4529081)

[brechtvanlommel at gmail.com]

Latest patch is quite well tested now on Mac and Windows, for
non-admin/admin installs, running from .zip with 2.57 installed,
migration of old files to 2.58, uninstall, etc.

One remaining issue is that when removing configuration files from the
installer, it will remove the files from the admin account when running
from a non-admin. I couldn't figure out how to get the $APPDATA for the
user that launched the uninstaller.

http://codereview.appspot.com/4529081/