“‘Impressionism,’ a new Broadway play about the healing power of Art, is in desperate need of the healing power of Cutting.” With opening night of the Jeremy Irons-Joan Allen vehicle pushed back two weeks, lead producer Bill Haber has told “investors that ‘Impressionism’ will be whacked to one act without an intermission (that’s one way of eliminating the mass exodus!), and that confusing sections created by what he calls ‘flashback moments’ will be trimmed and clarified.”