Trey Anastasio has broken free from the school of Phish . The legendary, floppy-haired frontman just announced he’s striking out on a quick acoustic tour this May and June in between his other group’s Sphere residency and nationwide summer outing (which includes five nights at MSG from July 22-29). At all solo shows — which he’s dubbed ‘An Acoustic Evening with Trey Anastasio’ — the 61-year-old Vermont native will be joined by his longtime collaborator and keyboardist Jeff Tanski. That includes