Shorten option name to "disableAutoPreview".
* src/main.c (read_options): Change option name to disableAutoPreview. * src/gpgoladdin.cpp (check_auto_vd_mail): Remove. * src/mailitem-events.cpp (EVENT_SINK_INVOKE): Don't call the removed function.
This also changes the behaviour to require a restart after changing
this option. Or well, to call the config dialog which will re-read
the options too.