DEAR MISS MANNERS: Is it rude to call a newborn by something other than their full name, unless invited to do so by the parents? We have given our child a four-syllable name. It is rare, but well-known from history, and it isn’t complicated. So pronunciation shouldn’t be an issue. I expected the child to try out and settle on an abbreviated variation eventually, as people do, but in the meantime, I expected to enjoy hearing the full name used. We picked it out carefully, and it has a lot of meaning for me. Instead, I have been blown away and offended as my in-laws and a few of my own family me…