Fixed bug that prevented GTK from storing printer driver preferences in the…

Fixed bug that prevented GTK from storing printer driver preferences in the print dialogue on Windows.

This is due to GTK trying to restore settings before the default settings have been initialized, so it's also zeroing out the size field for the driver preferences.

Also fixes the we were neglecting to save the device name in devmode, which caused the print dialogue to forget which printer you had selected. This is potentially disastrous because it can feed the driver preferences to the wrong driver.

This is the same patch I've applied to the 3.24 branch here: !396 (merged)