[dev] Patch: Enable bind params for Prepare() as well as Do()

Hi! While fixing some other stuff (patches for which I'll submit when I get around to it), I really wanted to use bind parameters for select statements as well as for inserts and deletes. So I just copied to approach used in Do(). I also removed LongTruncOK=0 and set LongReadLen to the same as the MaxFileUpload config setting. With the original settings, everything but the smallest attachments would be truncated on their way out of the database. Regards, -- Kristoffer.