When terpsichorean stars align, magic can happen. Such is the case with Hubbard Street Dance Chicago, a troupe founded 40 years ago by Lou Conte and directed by the indefatigable Glenn Edgerton since 2009. Edgerton comes to his role with a prestigious pedigree: Having danced 11 years with the Joffrey Ballet before taking the helm at Netherlands Dance Theater for a decade, his curatorial skills are in full flower as he and his 16-member troupe celebrate Hubbard’s four-decade anniversary.