LUCIFER - a NIR spectrograph and imager for the LBT by Mandel, H, Appenzeller, I, Bomans, D, Eisenhauer, F, Grimm, B, Herbst, T, Hofman, R, Lehmitz, M, Lemke, R, Lehnert, M, Leneen, R, Luks, T, Mohr, R, Seifert, W, Thatte, N, Weiser, P, Xu, W