fixed moc'ing errors with Boost 1.53.
identity matrices and transforms are now available as constant references to static members.
made it possible to disable autosave in appleseed.cli.

autosave can be disabled from the command line using the --disable-autosave option.  additionally, it can be permanently disabled by setting the "autosave" parameter to false in settings/appleseed.cli.xml.
fixed the behavior of the --samples command line option.

it was broken after the introduction of pixel renderers in 402c31359e4dce36c9350595ff1e15f1daa8ce17.