A group of Roxbury Prep students and their principal are taking their fight for a new high school straight to the top. They delivered packets full of self portraits of all 15-hundred students that attend Roxbury Prep to Mayor Marty Walsh’s office and to city councilors. They have a detailed proposal for a new high school to be built in Roslindale, but complain the Boston Planning and Devlopment Agency has been dragging its feet on the issue. They say the BPDA has been delaying putting the item on the agenda and taking a vote on the new school. Right now, students are split between two campuses about half an hour apart. They say that’s not good for student morale. WBZ’s Kim Tunnicliffe reports…