(This entry begins a series of 30 guest columns that will run during October, when optimism reigns supreme across the NBA. The theme will be “Five Reasons to Feel Positive About … ” We encourage you to follow the authors on Twitter and visit their sites. – CS) The squeak of vulcanized rubber against newly finished hardwood once again signals the return of the NBA. As training camps open around the league, veterans are refreshed, rookies are nervously ambitious and new