HESITATION MARKSRetirement never suited Trent Reznor. A workaholic who tempers his obsessive nature with a healthy streak of perfectionism, Reznor has put Nine Inch Nails in hibernation before, but the difference between the five years separating 2013's Hesitation Marks and 2008's The Slip and his previous extended gaps the half decade between 1994's The Downward Spiral and The Fragile, the six years between The Fragile and 2005's With Teeth is that Reznor didn't go