GERALD DECOCK HAS LIVED in a south-facing studio on the top floor of the Chelsea Hotel since 1994; the anniversary of his lease signing was last month. The hotel was a different place back then, presided over by the mercurial manager Stanley Bard, who, since the early 1970s, had rented its apartments to artists, musicians, writers, and the bohemian children of the well off; many of them were heavy drug users. When DeCock got his place, there was just one problem: Bard hadn’t let the current resident, Anthony Kiedis of the Red Hot Chili Peppers, know that he had to move out. But such were the good old crazy days at the Chelsea Hotel, which, long before DeCock arrived, had been home to Patti Smith, Janis Joplin, Jimi Hendrix, Dylan…