The LOFAR Two-metre Sky Survey: IV. First Data Release: Photometric redshifts and rest-frame magnitudes by Duncan, K, Sabater, J, Rottgering, H, Jarvis, M, Smith, D, Best, PN, Callingham, JR, Cochrane, R, Croston, JH, Hardcastle, MJ, Mingo, B, Morabito, L, Nisbet, D, Prandoni, I, Shimwell, TW, Tasse, C, White, GJ, Williams, WL, Alegre, L, Chyzy, KT, Gürkan, G, Hoeft, M, Kondapally, R, Mechev, AP, Miley, GK, Schwarz, DJ, van Weeren, RJ