The Boston Heat Wave Poetry Marathon is an annual weekend long poetry marathon-- lasting from August 18 through August 20-- at Outpost 186 in Inman Square.  Starting on Friday, poets are scheduled to read from 7pm through 10:30pm, Saturday from 12pm to 5:30pm and again from 7pm to 10:30pm, then finally Sunday from 12pm to 5:30pm. Each poet reads for 8 minutes. This event is free and open to the public. Friday night's line-up: 7:00 William Walsh 7:08 Jon Woodward 7:16…