Off Broadway’s Signature Theater has gotten a $25 million gift from the charitable org Pershing Square Foundation, with the funds to be put toward Signature’s ongoing low-price ticket initiative.In return, Signature has named its about-to-open new multi-stage venue after the foundation, with the three-theater building now to be called the Pershing Square Signature Center. It’s expected that the new coin will keep all ticket prices at the current $25 price tag for the next ten years, with a further decade of affordability-minded pricing to follow. Signature is poised to open its new $66 million home in midtown Manhattan next week. Among the initial shows on tap at the venue are a revival of Athol Fugard’s “Blood Knot” and “Hurt Village,” the latest from scribe Katori Hall (“The Mountaintop”). Pershing Square’s foundation is the charitable arm of Bill Ackman’s Pershing Square Capital Management.