- switch to cmake.
- add missing setusercontext() call in switchuser.cpp, now the ulimits
are properly applied when logging in.
- add support for bsd_auth(3) through auth_userokay(3). Now allows to
login via login_ldap/login_yubikey/etc...
- add support for consolekit, no need to do ck-launch-session in
.xinitrc anymore.
- make consolekit support at runtime optional, ie don't badly bail out
if systemwide dbus daemon is not running. Being discussed with
upstream.
parts based on a diff from 'johnw', ok ajacoutot@
