Relicensed from AGPL-3.0 to MIT, effective 1.3.1 (<=1.3.0 remain AGPL). The CSS content cipher and Stevenson title-key attack are attributed to their published cryptanalysis (not libdvdcss); all libaacs/libbluray/libdvdread/libdvdnav name references were dropped from comments while keeping the standard format/spec descriptions. Also bumps to 1.3.1.