NEC_-_PC_Engine_CD_-_TurboGrafx-CD

Added missing boxart

Added Madou Monogatari I boxart (#20)

Added missing redump boxart, fixed wrong boxart (#19)

Clean up of Gate of Thunder thumbnails and change for "4 in 1 Super CD" to REDUMP nomenclature (#17)

Merge pull request #16 from Setilla/master