Missing KeySignatures

The lib is missing 4 KeySignatures. For me I added those, but maybe you wan't to include them into your code (key.go):

func CsharpMaj() smf.Message { return key(1, 7, true, false) }

func init() { keyStrings[smf.Key{Key: 1, Num: 7, IsMajor: true, IsFlat: false}] = "CsharpMaj" }

func CbMaj() smf.Message { return key(1, 7, true, true) }

func init() { keyStrings[smf.Key{Key: 1, Num: 7, IsMajor: true, IsFlat: true}] = "CbMaj" }

func AsharpMin() smf.Message { return key(10, 7, false, false) }

func init() { keyStrings[smf.Key{Key: 10, Num: 7, IsMajor: false, IsFlat: false}] = "AsharpMin" }

func AbMin() smf.Message { return key(8, 7, false, true) }

func init() { keyStrings[smf.Key{Key: 8, Num: 7, IsMajor: false, IsFlat: true}] = "AbMin" }