Don't append extraneous terminating byte to sysex messages' data
Don't append extraneous terminating byte to sysex messages' data

When instances of MIKMIDISystemExclusiveCommand are created via initWithMIDIPacket, internalData will contain the terminating byte, so the data accessor should probably check if we already have terminating byte before deciding to append one.

bamboostick/MIKMIDI,alessandrostone/MIKMIDI,bamboostick/MIKMIDI,alessandrostone/MIKMIDI,alessandrostone/MIKMIDI,bamboostick/MIKMIDI