Coriolanus and the commoners on the Common
Coriolanus in triumph. Photo: Andrew Brilliant.I finally caught Coriolanus on the Boston Common (across two nights; it closed Sunday), and as usual I was slightly mystified as to why people lug out their lawnchairs once a year and swat mosquitoes while watching amplified Shakespeare. But maybe that's just what the groundlings like to do on a midsummer eve, I dunno.Well, the mob that watched the mob in Cor…