[Dovecot] Cache fields

[Alex S Moore]

Using 1.0-test51, or maybe test50.  I this message in syslog:
mail_cache_fields: Invalid cache field name 'MessagePart', ignoring

>From the what I see, MessagePart is the default value.  My
<sysconfdir>/dovecot.conf has:
mail_cache_fields = MessagePart

Thanks, Alex