By Luc Cohen and Brendan Pierson NEW YORK (Reuters) -Ghislaine Maxwell was sentenced to 20 years in prison on Tuesday for helping the sex offender and globetrotting financier Jeffrey Epstein sexually abuse teenage girls, in what a judge called a “horrific scheme” that inflicted “incalculable” harm on victims. The British socialite, 60, was convicted in December of five charges, including sex trafficking a minor, for recruiting and grooming four girls to have sexual encounters with Epstein, then her boyfriend, between 1994 and 2004. Speaking at her sentencing hearing in Manhattan federal court …