M'r makes more sense. The idea of the full stop at the end of the abbreviation of mister is that it's an abbreviation, so it should have one. In Britain, we're now taught to leave it out of Mr, Mrs and Dr, and I concur.
‘Sidewalk’ only makes sense if it's a pavement down the side of a road. For pedestrianised zones it makes even less sense than ‘pavement.’
