“I think the word we’re dancing around is gentrification.” So says Benn Ray of Atomic Books at the outset of this episode. What follows is a multidimensional portrait of a neighborhood in flux.  The 3600 block of Falls Road is a mix of longtime rowhome residents, recovering opiate addicts, and a new wave of business owners whose trendy boutiques have come to redefine a neighborhood that’s been in long economic decline.  Who does Hampden belong to?  The answer depends who you ask.