Boston’s Post Office Square has to be one of the prettiest small urban parks in the country. It may soon undergo a change, though, or at least a site along its very outer edge may undergo a change. Universal Hub’s Adam Gaffin reports developer Patrick Mahoney wants to convert 12 Post Office Square from offices to housing. Ditto for 10 Liberty Square around the corner. Adam has more on the proposals. … I guess the conversions are better than underutilized office buildings. And you have to wonder if other nearby conversions are on the way.