added a ising grid example: donut denoising
added a ising grid example: donut denoising

zxsted/factorie,pogren-oracle/factorie,melisabok/factorie,strubell/factorie,hlin117/factorie,digitalreasoning/factorie-scala-210,asubbaswamy/factorie,Craigacp/factorie,joprice/factorie,patverga/factorie,factorie/factorie,malcolmgreaves/factorie